1. Starfish Ethan

3. A starfish arm can grow back.

5. Sea stars are echinoderms belonging to the classAsteroidea[2]. The names "sea star" and "starfish" are sometimes differentiated,[3] with "starfish" used in a broader sense to include the closely related brittle stars, which make up the class Ophiuroidea, as well as excluding sea stars which do not have five arms (have Many arms), such as the sun stars and cushion stars.