Sponges are the only animals that if broken down to the level of their cells, can reassemble themselves. A sponge is passed through a sieve to break apart its cells. The cells recognize each other and reform into small new sponges.
Sponge life

Sponges are the only animals that if broken down to the level of their cells, can reassemble themselves. A sponge is passed through a sieve to break apart its cells. The cells recognize each other and reform into small new sponges.