Open brain coral question

I am after some info in regards to onpen brain coral. Will they expand open far enought to dammage them selves, ie such as into surrounding rock work.
Mine is opening up and realy touching alot of the rock near it could it dammage its flesh. It is opening much more then We realy thought it would.

 

They will in fact injure themselves if the rock is sharp or if the water flow is too strong causing friction/rubbing or irritation. They are known as a meaty coral and thus care should be taken to ensure that their tissue doesn't tear away from the coral.

 

some pics

running out of room in 55g

 

i hear you there.i also have a 55gallon display and theres only room in the sand for my one open brain.they should be in sand cause they will blow up big enough to move themselves around on the sand using their flesh.sharp rocks can hurt them but not garranteed.mines in the bottom left of the photo.much smaller than yours.also i thought i would mention.i no longer handle it without gloves.my hand felt very odd after touching it.

 

Open brain corals prefer to be on a sandy bottom vs the rock work. In the wild, when mature they usually are just relaxing on the sandy bottom of a reef.