A lost disc is a mystery disc that is created when a monster reverts back to its locked form. In the anime series, these discs are shown tangled in vines and stumps, probably just as a way to distinguish them from normal disc stones.
Lost discs lack the energy to be unlocked by normal means, and so the Searchers must leave them locked away until the day that Suzaku rises again and changes the hearts of all the Baddies sealed inside. The monsters are not actually dead, and thus their spirits have not passed on to the Paradise of Monsters. This would lead one to believe that the phenomenon of Lost Discs only occurred during the several hundred years between the end of the Final War and the end of Season 2 of the anime series.
Here is a list of the deaths that occur in the anime series:
- Captain Black Dino - Captain Black Dino and his two Black Dinos were chasing after Genki, and they jumped right off a cliff. Genki ran across the Black Dinos to get back to the cliff and the three Black Dinos fell off the edge into the river.
- Black Dinos - Fell into the raging river along with their captain.
- Captain Jell - Killed by Golem with a punch. The first monsters actually seen being turned into Lost Discs. (Note: A new Captain Jell was appointed afterward)
- Jell Troops - All killed by Golem with a series of punches, saving the unfortunate Jell for last. (Note: This was simply one team of Jell troops, as there were more at Moo's castle)
- Worm - Energy sucked out by the Seed Sisters. Jumped in front of Alan and Genki to protect them from this. Was unlocked after his revival.
- The Seed Sisters - One was killed by Genki and Suezo using a catapult to launch a boulder at her. She got out but died shortly after. The other two are killed by Alan using his whip after they killed his Worm. Their deaths are offscreen but we can see them as Lost Discs afterwards.
- Tiger's Pack - Moo's Dino Troops attacked and, using their claws, killed all of Tiger's pack except for Tiger himself.
- Captain Dino - Killed by Tiger with his claws.
- Captain Kuro - Tackled over a cliff by Ed. (Note: a new captain was appointed after him)
- Captain Clay - Killed by Pixie using her Lightning attack (often misnamed as Torpedo), joining the many other Lost Discs in the room.
- Gooji - Sucked into a whirlpool, punched into it by Golem after being taken toward it by Captain Horn with his ship
- Joker - Killed by Hare using his new Dragon Kick attack, smashing him through a wall.
- Captain Scaled Jell - All the Scaled Jells merged together to form a cannon, with Captain Scaled Jell as the driver. Pixie destroyed Captain Scaled Jell and the other Scaled Jells with an ultra-powerful Torpedo (often misnamed as Lightning or Big Bang).
- Scaled Jells - All the Scaled Jells merged into one to form a cannon, with Captain Scaled Jell as the driver. But Pixie used a Torpedo to destroy all the Scaled Jells.
- Gali - Killed by Mocchi with his new Mocchi Cannon attack. Was unlocked after his revival.
- Sandy Troops - Presumably killed when the Gali Hurricane caused Gali's castle to collapse (as they were not turned into lost discs from the Searchers fighting them or from the hurricane itself).
- Captain Black Worm - Killed by Tiger with Lightning, after confirming to him that his brother Gray Wolf was his enemy now.
- Undine - When she was swinging her arm at Golem to attack him, she knocked over pots of oil and it splashed on the fire and her arm, where a flame from the fire landed on her arm and set it on fire. She swung her arm around to get it off, sending small sparks of fire flying onto all the wood and setting the whole area on fire. Golem tried to save her, but as she had deceived him she felt she didn't deserve his friendship, so she jumped away from him and into the fire.
- Captain Jaggernaut - Killed by Melcarba with his spin attack.
- Jaggernauts - All are killed by the Melcarba using his spin attack.
- Melcarba - Genki stuck a metal staff on the Melcarba's head. Then lightning struck the staff and that killed Melcarba. Since Melcarba was an android and not a monster, he didn't turn to a Lost Disc, nor was he revived.
- Gray Wolf - Stabbed in the throat by Tiger with his horn. Was unlocked after his revival.
- Cabalos Troops - Some of them were killed by the Searchers, but one particular was thrown out a window by Naga and fell to his death.
- Stone Dragon - Sent falling into a bottomless swamp by Color Pandora with a Pinwheel Fireworks Attack, where he drowned.
- Captain Arrowhead - Killed when Jim ignited the thrusters on his boat, causing it to jump and land on top of all the Arrowheads, crushing them.
- Arrowhead Troops - Killed when Jim crashed his ship into them.
- Bajarl - Crushed when Holly detonated explosives causing a rock formation to fall on top of him.
- Naga - Hit by Mocchi using the Mocchi Cannon, slamming him into the wall, which broke under him causing him to fall. He held onto the edge of the castle, and though the others (Suezo extremely reluctantly) tried to save him, he instead let go, falling over the edge of the cliff. Was unlocked after revival.
- End Bringer - Kicked over a cliff by Genki.
- Shell Saurian Troops - Killed by Baku.
- Chariot - Killed by Baku in a beam struggle.
- Baku: Shot by Chariot using an energy ball, though Baku was able to destroy Chariot before becoming a lost disc.
- Metal Jell - Killed when the factory experienced an electric surge (caused by the Knight Mocchi shooting at the Searchers and hitting the devices instead) and exploded with him inside it. (see ep 40 for details)
- Knight Mocchi Troops - Killed when the factory experienced an electric surge (caused by the Knight Mocchi shooting at the Searchers and hitting the devices instead) and exploded with them inside it.
- Evil Hare - Many were killed by the Searchers. One of them is killed by Tiger using Lightning, and his Lost Disc was used by Jagd Hound as a decoy to make Lilim think that it was Tiger who was dead (which work too well as this also tricked other Searchers up until the real Tiger interferes).
- Captain Astro - Tried to punch Genki, who dodged, causing him to hit a wall, and the force of it knocked over tanks of water that washed Genki and Astro toward a waterfall. Astro fell over the waterfall, launching the rocket fist Genki was on to get him up to safety, realizing not all humans are evil. They and the Astros found him and witnessed him turning to a Lost Disc. The Astros turned good following this.
- Renocraft - Killed by the full force of Suezo's Tail Whip, Golem's Tornado, Tiger's Lightning, and Hare's Dragon Kick all at once, killing him.
- Captain Weed - Shot Seed Machine Gun at Lilim, but she snapped her fingers to signal the Gangsters to shoot him, mortally wounding him. He became a lost disc after killing Gangster.
- Captain Gangster - Stabbed by Captain Weed in the blue spot (his weak spot) using his tentacles. This deactivated the other Gangsters.
- Lilim - Stabbed offscreen by General Durahan with his broken sword as punishment for her betrayal, seconds before the Iron Bird crashed.
- Evil General Durahan - Killed when his Iron Bird crashed after being brought down by his own troops inside their ships, who serve Moo instead of him. Was unlocked after revival, but as just a head, and remained evil until the final batttle.
- Weed - Killed when Moo went berserk and destroyed his castle with his breath blast attack, sending the castle spiraling down toward the ground.
- Weed - Killed when Moo shot a powerful ball of darkness at the ship he and the Jell were driving.
- Jell - Killed when Moo shot a powerful ball of darkness at the ship he and the Jell were driving.
- Big Blue - When Pixie was mortally injured by Moo in his new form, Big Blue sacrificed his existence to fuse with her to turn her into Granity and heal her completely. (Note: As he was not turned into a Lost Disc, he would not be revived)
- The Phoenix - He and Moo destroyed each other, grabbing onto one another and vanishing in a huge explosion of light. The five monsters that fused into him would later be immediately revived in Season 3:
- Master Moo - He and the Phoenix destroyed each other, grabbing onto one another and vanishing in a huge explosion of light. His soul was sealed inside a Mystery Disk with Holly's father immediately after.
- Captain Jelly Gaboo - Killed by Mocchi with Mocchi Cannon.
- Jelly Gaboo troops - Killed by Mocchi with Mocchi Cannon
- In flashback, a Mocchini is shown to be accidentally killed by Most with Cherry Blossom Blizzard.
- Moo's evil soul - Charged at by the Phoenix while powered by the energy of his allies, recently including Durahan and his gang, destroying Moo's evil soul forever.