I'd this please

[Junior84]

Does anyone know what this is its growing alk over the rocks in my tank

 

[cracker]

some type of sponge maybe? or maybe Macro algae.

 

[cloak]

It looks like some type of red macro algae to me as well.

Just a guess.

http://www.saltcorner.com/AquariumLibrary/browsegroupspecies.php?GroupID=105&filter=0

 

[Junior84]

K thanks it kinda feels like a sponge... little hard but not slimy