What is this?

hey guys! I'm setting up my new tank and this is my first saltwater tank and I bought a bunch of liverock today...Once i put this rock in i noticed a few things and im not sure if theyre something i should worry about or not.





I realize in this one the white is old, dead, bleached coral but what are the green sacs?







this little thing i jus saw floating around..its not attached to anything either