What the heck is this?

[harlequin]

I had given my gf some rock for her tank from mine and these weird feathery clear things all of a sudden are growing all over it and spreading to whatever is touching the rock. Whatever it is the blenny who has cleaned every rock in the tank avoids this one. Here are some pics

 

[harlequin]

...

 

[sweetreef]

was that part of the rock not seeing the light?

 

[harlequin]

it was in direct light. True the lighting is not super powerful but it is enough to grow zoos in.

 

[sweetreef]

I have the same stuff its some kind of sponge but mine is on the rock where the light dont hit it...

 

[mudplayerx]

Looks like a fungus or a water mold.... but I have incredibly limited knowledge on marine species.

 

[fishcake]

sponges!