Trochus snails - Trochus sp. - are an active part of the clean up crew. They resemble the size and shape of "turbo astrea" snails, but Trochus have whiskers radiating from their foot. They clean glass and rock, and can be seen moving on the substrate's surface. They rely on film algae for their primary food source. Unlike Astreas, Trochus are more likely able to right themselves if they fall off the glass or rockwork onto the sand.