What about these critters in the sand?

[Reef Monster]

Found these guys after removing most of the sand during my tank transfer. Amphipods? I sprayed a bunch of water and vinegar inside the tank to clean it before I noticed these guys. If they are beneficial, are they still ok to scoop up? I'm completely new to this.

 

[P-Dub]

Amphipods. Yes, beneficial, for the most part. If they are still alive, scoop up in a net, rinse with clean tank water and put em in your tank or refugium.