Failuresaurus is a slimy, zombie-like mob that is spawned when a culture vat fails. The first time one spawns, an "Epic Fail" achievement will be achieved by the player that put the DNA in the culture vat.
When a culture vat fails, a failuresaurus is produced. They behave like zombies, as they are hostile and will follow and attack any player. They leave slimy failuresaurus trails in their wake as they travel. Though mostly similar to zombies, they do not burn in sunlight and do not despawn. This makes failuresaurus a threatening pest to the player, or sometimes if fenced in, a cute pet. They have the ability to climb walls, however, so any fences should be made tall.