Is started a new 40gal tank a few months back. One of the live rock is growing a thick grass type plant out of it. It has not spread to any of the other rock as of yet. As it looks so far it's not the stringy type of grass but it may be how it starts, I am unsure. I have three other fish tanks and I've never seen anything like this growing out of the rock. Any advice will be greatly appreciated. Thanks, have an awesome day!!