A couple hours ago, there was this poop or worm thing on my rock, and it was first at a open “C” shape (seen below), then a couple hours later, it was at a “O” shape or closed (as seen below). I turned off the light, and later, i no longer see this on my decor. Is this a worm or poop?! Was the shape changing normal and it disappearing when light was off? Can it be from a fish from eating the thing so it prolly disappered?!