Yeah, I have chitons, limpets, asterinas, you name it. Asterinas don't usually get big as when they would otherwise grow further, they split instead, so the one I have (must be 0.75 of an inch end to end) is yet to split. I've a billion of the smaller ones that split more readily.
I've also got Nassarius snails that breed all the time, I've constantly got hundreds of them. I should start selling them actually, as they fetch about a quid each!
What does the baddie starfish look like?
I could send out "Goodie bags" of CUC like that, Brittle stars, asterinas, nassarius snails, stomatella snails... That's what I like most about having a fairly nutrient rich tank, I have quite a lot of fish, and quite a lot of tricky feeders, so it's inherently a well fed tank, which leads to lots and lots of life bursting out of every orifice.