I've got a bicolor "hammer" that looks like that! It's one of my favorites. Perhaps there are more species of euphylia... I was thinking the exact same thing you were, because in some places it looks like a hammer and in other spots it looks like a frogspawn. It seems to be the fastest growing LPS in my tank, too (other than my candy canes). I started with 3 heads and now there are 6 and some babies around the edges...? I don't know, but looks great to me!