So I have had this tank for about a year now and there have been no additions that I can think of (last was an urchin a few months ago). I left my tank in the hands of my hubby for a week and came home to these little larvae/free swimming parasites? There are lots of them and they are super speedy making it hard to get a close up. I don't have any breeding pairs of anything except maybe trochus snails in my tank. What the heck could these be? Excuse the ridiculous amount of photos and videos they are just hard to get so I figured some may be better than others.