Is this tiny black starfish good or bad?

[Brett S]

I just got some snails and this little guy came in the bag with them. He’s pretty tiny. Maybe 1/4 of an inch across. Is he good, bad, or indifferent?

 

[homer1475]

Asternia star. Throw it out.

While some are good, some are bad and we have no way to tell the difference. Best to err on the side of caution.

 

[stanlalee]

Even harmless ones cause a few problems. The main one is quickly proliferating into plaque like numbers. The second problem which may not be a problem is that they literally demolish coraline algae growth. That is good for glass and pumps but your 13 year old live rock that was once covered looking fresh off the initial cycle not so much. Most do not bother healthy corals BUT if an sps becomes compromised you can forget about the compromised section as they quickly pounce to unhealthy tissue.