Coral Banded Shrimp
If you want to see guests react strongly, get a Coral Banded Shrimp (or Banded Coral Shrimp) - Stenopus hispidus. Molting every few weeks can give you the momentary impression that suddenly you have two, their molt closely resembling the original creature. It will consume Peppermint Shrimp, Arrow Crabs, and Flame Scallops unfortunately, but my Cleaner Shrimp has eluded it for some time. The bright colors and its agility make it a fascinating addition to any reef tank.