Are sea stars and sea urchins segmented?

Yes they are. They are both echinoderms

A sea star is called a sea star simply because of where it lives (the sea) and what it looks like (a star), simple!

Sea stars favorite food are mussels, they grasp the mussel with their tube feet and pry it apart. They then eject their stomach into the open mussel and digest the soft mussel body. Once digested,...

both of them live in the ocean every where and they are echinoderms

No. Sea urchins are animals, which eat algae. They use there spines to make sure no fish eat them, and their mouths are on the bottom of them. They move around on almost invisible legs.