Algae growth or something else??

[jlynne231]

It may be tough to see in the picture, but there is a gray/white hair/fiber
growing on my LR. It is growing on many pieces of rock. The location in the tank does not seem to matter. It is on the rock up high, in the sand, left and right sides of tank, front and back pieces of rock.
Ammonia 0
Trite 0
Trate 10
pH 8.3
temp is 78
SG 1.025
Anyone have a clue? Only other symptom of tank is some very unhappy looking hammer coral and bubble coral

TIA

 

[mr_X]

it looks like sponge to me. someone suggested foramanifera, but these have shells. i know the stuff in your image to be soft to the touch.