Slug pod?

I have a newer tank and have been watching my pod population grow with interest. Today, while looking at the copepods on the glass, I noticed something else. They're just a little bigger than the copepods and they glide like a slug instead of quick skittering jump of the 'pods; slightly elongated with a forked end.



They concerned me because they seemed to be chasing/trying to eat the copepods. They weren't successful (at least while I was watching), as the copepods were much faster. But I was wondering if anyone could tell me what this is and if it's harmful?