I found one on the bottom of a rock. It does eat snails. Can move very fast on the rock and 'pour' into tiny holes. Once in the water column it ruffles, so I thought I had an octopus from the angle through the tank I saw it and how close my hand was too it.
Interesting creatures.. I saw one diving into a pinpoint sized hole in the shell of a turbo snail and got it out that way. No more piles of snail shells since