Black lines on rocks? Worms or poo?

[aaa1234]

Hey everyone,

So this morning before work i looked into my tank and started to see these black lines forming on all of my rocks. They are on my dead coral skeletons and on my live rock. I didnt start seeing them appear until after i put in my Cleaner Crew. Could these lines just be poo left behind by my generous janitors? Or is it something that i need to take care of? Help!

-Sven

 

[Reefmack]

A pic would help, but I'm guessing if you have some big snails like Turbos it's just snail poo.