What are the examples of gemmules?

Gemmules are asexual reproductive structures produced by certain freshwater sponges, such as Spongilla. They are typically spherical and consist of a cluster of cells surrounded by a protective coating, allowing the sponge to survive adverse environmental conditions. When conditions improve, gemmules can germinate and develop into new sponge individuals. Other organisms, like some cnidarians and certain algae, also produce similar structures for reproduction and survival, though they are not termed gemmules.