I did the maintenance thing today then was admiring looking through pristine glass to find this ball with white dots protruding from it rolling around the sand. When it stopped, I could see the tentacles that hold the small white dots moving. I got the vacuum ready after taking these photos. By the time I went to syphon it out, it was gone. Maybe under a rock. Maybe got eaten. The blurry photo is with full zoom so you can't use that to gauge size. The next photo is normal zoom. Diameter is about 1/2". It seems to have almost neutral bouyancy when off the substrate but tends to settle to bottom then roll around in the currents.
