I had my anemones encroach on a large (8+" skeleton) hammer. The anemones and hammer lived in moderate peace for several years. I say "moderate peace" because the hammer would have nematocyst-filled bulb-tipped sweepers on the side that faced the closest anemone. Then, within a few days and without any warning signs I noted, the hammer retracted, slimed up and died.
So, for what it's worth, I don't recommend anemones and euphyllia species corals as roommates.
Kevin