the tentacles you see are the ones they sting with. they are all euphyllia's they wont sting each other. they will sting the heck out of other LPS though I had the unfortunate expirience of knocking a small frogspawn into the middle of my fungia the damage was quite severe and almost instant, and took several weeks to recover. corals dont wait to have a bad day and sting the second they contact what they deem competition nematocysts are fired. the same fungia had previously stung a mushroom into receeding awayfrom it, so the verdict is, Euphyllia stings harder than fungia, fungia beats mushroom, and euphyllia doesnt care about euphyllia (kinda like rock paper scissors when its written out like that.