Please ID these hitch hikers

[Zoidberg]

Thanks ScubaSteve,

#2 doesn't move very often. I'm pretty sure it's just one critter. I've seen it in a few different places on that rock and it's always sitting there not doing much.

#3 is tricky to photograph right now. I watched it for a while and the other side looks like some sort of clam. It's got bilateral symmetry and pulls itself along with a foot/tongue.