Snails are great algae grazers, but sometimes their feeding activities can lead to multiple headaches in our aquariums. Besides having a propensity to knock over loose coral frags, snails can also damage the glass and acrylic walls of our tanks. Because the walls of the aquarium grow algae, snails are constantly wandering off the rocks and onto those walls in their nonstop hunt for food. Normally, their raspy tongues take care of algae without an issue, and they just move on. But we recently discovered something that snails do that could scratch the tank. We noticed an odd noise coming from my nano aquarium that persisted for days before we knew what it was. Then, we randomly discovered the source. The banded trochus snails in the nano were sitting on the glass, twisting rapidly back and forth. Their shells were rubbing against the glass, creating an annoying noise that most likely doesn’t do anything positive for polishing the glass. There’s not much we can do to prevent this activity, and we’re not sure if it is related to eating algae or just random things snails do. But, it is something we’ll need to keep an eye on.