I somehow have the impression from the many Dhamma talks and books I read that the Buddha once scooped a palmful of water and ask the monks if there is any beings there. Then the Buddha declared there are a lot of beings even in this palmful of water. I am not sure what’s the lesson to be learn here.
This is sometimes used in some Buddhism and Science conversation to say that the Buddha predicted microbes way before microscopes were invented.
Yet, I cannot find the source of that story in the suttas. I am starting to suspect that it’s something which arises later and is likely not a prediction of microbes by the Buddha. Surprisingly, even google turns up empty, so it might have been a small urban legend in Buddhism here.