I don't know if my cat has worms!?

I just cleaned the kitty litter box (which is in the basement) and I found 4 very very small dark brown worms that were curled in a U. Not IN the box, but about 2-3 feet away from it. I have read that tape worms are white, so Im assuming thats not what they are....but WHAT ARE THEY? I'm so creeped out and not sure if they are coming from the box or just maybe the basement? Someone help please!!