Sounds like everything got there with no freezing
. Yeah, there will be lots of possible life. I have mini brittle stars, mini worms, pods, bristle worms, snails, crabs, and lots of other critters in my tank I got from other tanks in town and on my LR. They might start to show up in time, if you don't have them already. I have more LR, and I'm trying to keep stocked up, so if you know anyone in your area that needs some I should have some available for 4-5$ per LB. If the crab you see in the rock has sharp looking pincers and not the algae pincers of a emerald, remove it. You could try and remove it with a crap trap, but every gorilla crab I had I removed with my hands, watching my tank at dawn/dusk.
Matt