Sea cucumbers (Class Holothuroidea) are echinoderms.
They are tube feet and are also symmetrical along five axes.
Unlike sea stars, they have no arms or obvious spines.

To repel predators, some sea cucumbers expel their innards.
These are eventually regenerated.
However, not all sea cucumbers can expel their innards.
Those that do are not able to eat until they regrow their innards.