Is this a parasite?

[gzilla]

What are these ? i used to spot a few but at night i found a more than a dozen of these, they seem to hide in the rocks i have. are they harmless ? do they eat coral ? what fish can eat them? how do i get rid of them ?

 

[Ben.QLD2]

Amphipods. Beneficial reef fauna.

 

[kevgib67]

+1 amphipods, part of your cuc. I didn’t get any of these as hitchhikers so I bought them.