its a sponge , a filter feeder
do a google search on ther tupperware method for feeding suncorals and dendros , basically use a tupper ware container or measuring cup filled with tank water and pollute the hell out of it with mysis,planton, pellets etc.
float the container in your sump or tank and place the suncorals in there and leave them there for the day , do this a few times and they will swell up and start to feed reguarily, suncorals should be out for most of the time , the longer they are closed the harder it is to coax the out for food
once done with the container thow the food into the garbage , now you have a fed suncoral or at least a feeding response and no pollution to your tank what so ever
it works like a charm and can even bring back the worst of them to life
a suncoral can be trained to come out at the same time every day for food or even to saty out all day if fed often enough
if it helps any the branching yellows are hardest to keep , then the branching orange . the matted yellow and oranges are easier than the branching species are.
black branching is the easiest to care for and can go with once a week feedings, however daily is best.
once a suncoral loses its stalk color it never regains it back only new growth will be colored
hth
cheers
denny