Mushrooms Dying?

well I picked up a mushroom rock from my LFS and the first night one of the mushrooms was all torn apart(it looked fine when the lights were on) this happened about 2 to 3 hours after the lights shut off. by the morning it had totally fell of the rock in a blob mess and has dissolved.the other mushrooms on the rock have opened up but I just noticed a smaller one on the back starting to fall apart and dissolve in the same manner, is this common?

the tank is a 55 gal w/pc 65x4. I put the mushroom rock about half way down in the water.

I have 2 diff star polyps, brain coral, and button polyps that are fine.(had them about a year)

 

plus I noticed some of the mushrooms excreting some wispy white stuff from their mouths. tried to get pics but they didn't come out that great.

 

They are called mesenterial filaments. Something is attacking them so they are attacking back. Move the rock. I'm guessing the brain's sweepers are hitting it at night.

 

the brain is on the other side of the tank but it was between button and star polyps about a half inch or so on either side.I know what you mean about the filaments, but the stuff they are execrating is like a whitish brown goo and it breaks off, one of them keeps extracting filaments (coiled up looking technicals) , I did what you said and moved the rock to the bottom they seem to be better now but one keeps sending out its filaments. the LFS had them under MH and now their under pc's could this just be stressing them till they get use to it?

also this is probably a stupid question but the rock is crowded with mushrooms will they fight each other for space?