Justice League of America, Vol. 1

Neverwas, a giant, self-aware single celled creature from Earth's prehistoric past somehow finds a way to the present where it comes into conflict with the League. It replicates by dividing, forcing the League into a battle through time as its several bodies traverse the timestream, at one point stranding Superman in the past. The League rallies, however, and manages to send Neverwas back to the past.