A bug in my tank??

[Turnage]

I have a Biocube 32 that is about 2.5 weeks old right now. It has 20lbs of live sand and about 20lbs of Carib Sea Life Rock. Anyways I was doing a water test when I noticed a small bug crawling on the rocks. It's about the size of a grain of rice. See pictures. How in the world did it get in my tank and is it a good guy or bad guy?

Cheers

 

[Mrs. Herbert]

Maybe a pod, kinda hard to tell from the pictures. Pods are a good thing.

 

[Bryson.bobby]

Looks like an amphipod

 

[KJ]

Look like Amphipod Gammarid. Good CUC and fish food