questionable growth? please help

I have this (organism) growing on a couple of pieces of my live rock and i'm not quite sure what it is. When I got it, I was told it was chicken liver sponge, but upon searching the web I find that it does not resemble chicken liver sponge at all. I was hoping that I could at least get a general idea what it is and if it is at all desirable to have in my tank. Any help would be appreciated and thanks in advance.

 

I've never heard of chicken liver sponges but that doesn't mean much I do think that what you've got there is a sponge though and if it is, it's completely harmless so I would just leave it be.

 

Sponges are filter feeders and also don't require intense light. They also need to be kept in water during transition from store to bag and bag to your tank to survive as their system can't handle air bubbles!