This is a coral banded shrimp, a popular crustacean in saltwater reef aquariums. It uses the "mini claws" to pick parasites/fungi off nearby wounded fish to prevent the spread of infection and therefore saving the fish.
This coral banded shrimp that lived in my aquarium for about 8 years. It was always cool when he would molt. I remember the first time it shed its crust it looked like it had replicated itself. They also pick parasites and fungi off wounded fish to prevent the spread of infection. Very cool and hearty crustacean that doesn't bother many different types of corals. If you get one for your tank, be very careful to check your water for copper, and use a neutralizing resin if you don't have access to an R/O source. Also no fish medications containing copper (commonly used to treat "ick"). They are very sensitive and will quickly die if exposed to copper, similar to many invertebrates.