Wife Sees a "Bug"

My wife has (thankfully) really taken to the new tank. She was watching the tank really closely this evening and exclaimed, "Eww! What's that bug?"

"Bug?" I asked.

"Yeah, there's a little bug in there."

She said she saw a tiny "bug" crawl out of of a piece of live rock, scurry down the rock and into another little hole in that same piece of rock. The holes she pointed out were no bigger than a big pin head, so this is a small critter.

In describing it, she said it was one shape - not segmented. That it had legs - "at least 4," and that it was tiny, "like a little ant or bug."

So.... What could this little critter be? I added some live rock a while ago - maybe 5 weeks ago. I assume this, whatever it is, came along as a hitchhiker?

What do you think it is?

sounds to me like copepod.. good sign tank is maturing..

+1 but copepod are smaller but amphipod or something like that are bigger they look like rolly polly

+2
Think of em as free CUC and fish food.