Animal Phyla Question?

Snail or clam might be easier to find for Mollusca than squid. Look in the seafood department of your market. Basically any seashell would do. For arthropods, an insect or spider would easier to locate than a lobster. Also, shrimp in the market. Or, if you live near an ocean shore, barnacles on the rocks. You can dig up an earthworm in any garden or lawn. You won't find roundworms or flatworms there. Actually there are roundworms in soil, but they are extremely small, only a few millimeters. Surely someone you know must have a piece of coral on their bookshelf or such. It's a pretty common decorative item. Echinoderms would be harder to find if you are not near the ocean. Starfish would be the most likely to find. Flatworms is going to be tough. Most of them are internal parasites. The only free living ones are Planaria, tiny little worms found in fresh water ponds and streams. It is possible to trap them, using a bottle with some bait in it.