["D"]

Does anyone know what this maroon algae is? It is over taking my tank. When I pull it off the rocks it comes off in clumps. It compresses when squeezed and for the most part returns to it original shape when let go. If you crush it in you fingers it will break apart.

[zhenya]

Hi "D",

Welcome to Reefland!

I don't know what this algae is, try this link and search some of their database. What is the origin of your live rock (Indo-Pacific or Caribbean)?

["D"]

Thanks for the link. All of my live rock came from Fiji.

[zhenya]

You can narrow your searches via Google by locale then, select images as a result of searches so you can compare them to what you have in your tank.
Brief search showed something similar here but it is far from being identical.
Google Image Result for http://www.callalabay.org/wp-content/uploads/redalgae3.jpg

And here's a page with results of search using Google red marine algae - Google Image Search

There is roughly 4000 species of Rhodophyta, so I imagine it would be very difficult to identify it. I am sure you want this algae gone, so I would suggest some manual removal at every water exchange and making sure that you can starve this algae by reducing nutrients as much as possible. That's just for starters.
I know that Reefland had similar problem with "red algae from hell" and if I remember correctly he wrote a series of articles for our magazine RHO(now defunct, unfortunately).

Nuisance Algae In The Reef Aquarium Part III - Reef Hobbyist Online Magazine

I wish you luck in your upcoming battle, "D"!