I see from previous posts that we are not limiting this thread to "life forms" but also meteorological phenomena. Well, I don't know how to classify this one, unless it's a geological phenomenon.

I was walking with some friends along a built-up path through the flood plain of the Mississippi River near here (St Paul, Minnesota). A marshy area surrounded us, and the river was not far away. We stopped to rest, and for no particular reason, I began staring at a shallow puddle next to the path. Actually, there were two puddles, and water was slowly trickling across some mud from one puddle to the other. The far edges of the puddles disappeared into the tall weeds.

As I watched, the water gradually came to a stop and then changed directions and began flowing the other way. After a few minutes, it reversed directions again . . . and again . . . and again. I think we watched through 2 or 3 complete cycles. I didn't time it, but I'd estimate it took 10 minutes or so per cycle. Then we got bored and left.

The experience was sort of like watching paint dry. But wouldn't YOU watch paint dry if it dried, and then got wet again, and then dried again, all by itself with no apparent reason?