What Are These Bugs?

My family likes to collect rocks, such as arrowheads or just old creek rocks. My fiance has several of these rocks laying in our window sill to display. If you pick them up and look "closely" you can see a quick, tiny bug smaller than a flea dart off! I can't tell how many legs it has, but it is almost a yellow orange, off white color? I have not seen them anywhere else. It is as if they have a hidden world living under his collectable rocks.

Thank you. Sincerely.

Girl with these rocks and such.

By Courtney