Well, during the day they hide it caves, liverock, etc.
But at night they come out to scavenge the tank...
Good point, but I'm not how sure they really stir up the sand.
I love my conches. They do a great job, don't bother anybody, never even think about predation and I like watching their little eyes peeking out of the sand.
They are very small, only about 2 inches long now. When I bought them about 18 months ago they were about 1/2 inch smaller. They are in my 180 so I think it will be a long time before they outgrow it.
Moby