How do I get rid of this gray slim sponge?

[pbanda]

This gray stuff has been slowly taking over my tank for the past 2 years. My sps can't compete with it... What is it and how do I get rid of it? I am at the point of taking the rock out and sunning it ouside for a while to kill it.

 

[LeslieH]

A combination of scraping & sun should do it.

 

[Jojoyojimbi]

it's the blob

 

[pbanda]

Scrapping is a lost cause... is the sun the only option? I don't think anything will eat it...