Black algae? on zoas...

[leonel619]

Hey everyone. Was wondering if anyone had an idea of what this black stuff is on my zoas.
I went ahead and closed them so I can get a decent pic. You can see it on the stalks. Some have it more than others. The colony is always open abut I have noticed that they have gotten a bit thin.
Any ideas on what this could be? Should I dip them?
Thanks.

 

[Tysob44]

There pooping

 

[leonel619]

There pooping

Is that what it's on the stalks?
I know that they expel waste from their mouths but not sure about the stalk of the zoa.

 

[loves2reef]

doesnt look like algae but you could always try a peroxide bath.