New to saltwater

[rollingstones420]

That picture didn't look much like the lobster I saw at the store. The one I saw had much bigger pinchers and lacked the purple. It doesn't really sound like it either. The one I saw was out and walking around and it was like 1 pm. Maybe a different kind of reef lobster? I'm sure it's a common name thats thrown around alot. And about the mantis shrimp. Where might I find one?