So its only been in the tank a couple of days, but I'm not sure if its looking unhealthy? No experience with mushrooms....any thoughts? He's at the bottom of a Fluval Evo 13.5. Give it more time or try other placements?
Try dropping a tiny amount of food on it, something like pellets will work or anything that will sink.. those things prefer higher nutrient established tanks and it looks like yours is probably brand new. Be aware that they can be very invasive so I would keep it off your rock work and they also can also potentially cause problems to other coral via chemical warfare, I had a small colony I had to remove from my tank because it was killing everything around it.
I'll give that a try....thanks. Yes, I put it in the sand bed, and based on what you said I think I'll keep it there so it can be removed. And yes, new tank!