Each of the invertebrate groups has its own subpage(s), and a few representative pictures to help you figure out what that group looks like.

Group	Sample Photos
Anemones
Bivalves
Cnidarians (corallimorphs, hydroids, zoanthids)
Crabs and Hermit Crabs
Feather Stars
Jellyfish
Lobsters and Shrimps
Nudibranchs
Octopuses and Cuttlefish
Sea Cucumbers
Sea Slugs  (other than nudibranchs)
Sea Snails
Sea Stars
Sea Urchins
Sponges
Tunicates
Worms Christmas Tree Worms