I was looking at my tank last night before the normal lights went out and only the moonlights go on and I noticed a very small jellyfish like creature. Unfortunately, it moves too quickly and gets moved around with the current in my tank so I was unable to take a picture. I thought at first that it was an extremely small baby polyp (about the size of a brad nail head) that had detached from a piece of rock but upon closer inspection, it was actually pulsing it's "head" to move throughout the water column. I was wondering if this actually is a jellyfish and if so, is it okay to leave in my 12g nano tank? I hope it is because it was really amazing watching this "thing " last night!