Is this algae?

[Jettjack]

Notice this growing on the rocks in a small section should I be worried? It’s like black stringy I have a little bite of hair algae growing in the sand but it’s not his.

 

[vetteguy53081]

Notice this growing on the rocks in a small section should I be worried? It’s like black stringy I have a little bite of hair algae growing in the sand but it’s not his.

A pic under white lighting would help with clear i.d. but preliminarily looks like chaeto algae or possible strands of derbesia (similar to bryopsis)