Mushroom Coral: Green

I purchased the "17244 Mushroom Coral: Green" and was amazed at the amount of mushrooms I received! At least two different types all over a medium rock plus a very small rock with a couple more on it (and a little guy on the loose that found himself a good spot in my tank). There was also a surprise on the medium rock that I'm unable to identify - It's a smooth flat encrusting variety, spread over an area of rock, some patches of rock show though it in a few holes and it also has peaks that put out hairy tufts at times, I'm assuming the hairs capture nutrients. Can you tell me what this is? I like it but can't ID it!