Small crustacea

[aquadonkey]

Hi there - can anyone help me id some tiny shrimp (maybe)?
I went through a phase when my 7g was crawling with small Crustacea - mysids maybe? Well - that phase is over and I have many less; however, there are still some larger (4-5mm) ones living on the sand bed. A couple weeks ago I witnessed a battle between a couple of these guys and one of those brownish small brittle stars (bigger than the whites). Was pretty cool actually. And today I just watched this little shrimp building a burrow - carrying around medium-large pieces of sand. Also pretty cool!
Any thoughts?

 

[aquadonkey]

And.... no, I don't have a picture
This is beyond my camera phone photo skills....

 

[museumguy]

Probably Amphipods of some sort. Pretty common in a lot of tanks, they like to hide in and round rocks, algae, etc.

Good for a tank, lots of critters in aquariums will eat them.

 

[aquadonkey]

Cool - thanks! Looked up a pic and that's it. I guess I have a ton since there are no fish in there to eat them. Really fun to watch! Like a tiny, non-destructive pistol shrimp