There are a ton of different types of mushrooms when I investigated this one I didnt come up to anything conclusive. But to me it looked like one of 2 a tonga mushroom like a watermelon of a different color morph. Or a Rhodactis of a different color morph. IMO its the second one but I am by far not an expert so its just going on visuals. The specimine in the pic I posted is about 3 times larger than that now as it has acclimated itself to my tank and is very happy. Looking at the lack of color in yours (almost see thru) I am leaning towards them being bleached, but most likley the same species as mine.