A tiger conch could work. But linikia starfish will starve to death, same with the sand sifting sea star, a chocolate chip starfish would eat your coral, a horseshoe crab will get to big and will starve unless you alter your feeding schedule around it, and most gobies will get sands all over your rocks. If your sand bed isn't very deep in that ten gallon then I would say not to get any sand sifter a because the surface area is so small that it would be rare to get an anerobic pocket in the sand bed. You should just let it be with the nassarius snails.
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