Starfish possess one of the most extraordinary regeneration capacities in the animal kingdom.
These marine echinoderms can regenerate not only lost arms, but some species can regenerate their entire body from a single arm, as long as it contains part of the central disc.
The regeneration process can take from several months to more than a year, depending on the species and the extent of the damage. During this time, they develop completely functional new internal organs, digestive, reproductive, and nervous systems.
This ability is due to specialized stem cells called 'neoblasts' that can differentiate into any type of cell needed. Some species, such as the Linckia starfish, can even undergo asexual reproduction by intentionally fragmenting, where each fragment regenerates into a complete individual.
Source: Marine Regenerative Biology
