They seem to reorganize their tissues and then just keep living.

The discarded fragments of this creature apparently refuse to die, leading researchers to claim immortality

Can Cells from a Sea Cucumber Live Forever?: What scientists are learning about immortality from a humble marine creature

Severed fragments of a sea cucumber kept living and thriving instead of decaying, puzzling researchers.

They seem to reorganize their tissues and then just keep living.

The oceans are home to many of Earth's longest living creatures.