Mushroom rock

Question
Hi there.  Just set up a marine aquarium and was advised by the shop to put in  live rock and a mushroom.  The mushrooms have shrunk and gone from purple to a blueish colour.  What am I doing wrong?  The nitrite level is at 0.1 which i was told is ok as it will settle really quickly, and the temp is 24 degees C.  Theres nothing else in there yet except a hermit crab abd a tiny snail. I really need some help!  Thank you!  Barratt Waugh.

Answer
some local fish shops will tell you things just to make a sale, your tank needs to be fully cycled before you add anything thats alive.

ammonia should be 0
nitrIte should be 0
nitrAte should be between 0-20

you use live rock to cycle your tank (if you don't know what i mean by cycle look it up on google) too long for me to explain on here.