When I first setup this tank, approximately 4 months ago after adding LS (fine Fiji pink caribsea arag-alive) I found a few hitch hikers (small disk animals) one was green, the rest have been pinkish. They attach very securely to LR or glass and are often in the sand as well. My first guess is sand dollars and I can’t find anything else that closely resembles them. Thank you in advance for any help.
