Spider Conch.

They are only suited for larger tanks, with a large sand bed. Spider Conchs have an amazing shell, that is sure to make people notice. 

They are an excellent cleaner, and substrate stirrer. They will consume hair algae, film algae, detritus, and many cyano species as well. You can feed them sinking soft algae pellets or spirulina when the tank is clean. They are a hardy species, but do best within tanks that are at least a month removed from the end of the cycle. The Spider Conch feeds through a "trunk" like mouth,  and eyes that  are on long stalks that can move independently- making them an interesting creature to watch.