I am a big fan of Trochus snails as well. But, whenever I get Astrea snails, most of them become murder victims, and the hermits always leave one witness behind for some reason. I also have a watchman goby that does an excellent job sifting sand, but he does not play well with others. He also occasionally redecorates the tank and carries hermits, snails and smaller pieces of rubble around in his mouth.