Time to learn something!
1. Go to Wikipedia.
2. Click on “Random article” in the left-hand sidebar box.
3. Post it!
Valvatida is an Order of starfish in the Class Asteroidea, which contains 695 species in 165 genera in 14 families. The Order encompasses both tiny species, which are only a few mm in diameter, like those in the genus Asterina, and sea stars, which can reach up to 75 cm like species in the genus Thromidia. Almost all species in this order have 5 arms with tube feet. This order is primarily identified by the presence of conspicuous marginal ossicles, which often characterize most of the species. Clamp-type pedicellaria are usually being the main type of pedicellaria in this group.
The Wikipedia item has some nice starfish pictures.