I just got my order of little baby Siphonaria limpets, but I'm concerned: a couple of them have ventured up above the waterline. I didn't think they were an intertidal species. Is this normal behavior? And if so, how should I deal with it? Should I leave them be and they'll venture back down on their own, or should I move them back underwater when I notice one above the waterline? I've never had turbo snails or anything, so I don't really know how to handle inverts with a habit like this.