I was away for 5 days and came back and found these on the side of my overflow return box. I can not find them anywhere else. What are they. They kind of look like Nudibranchs, but not quite and really not like flatworms. The only new thing added was a bunch of Cheato that was generously given to me 7 days ago by a fellow reefer. Could they have come from this? Are they friend or foe?
