Hammer coral growth

[Baldy]

I have a question regarding some hammer coral in my tank. when i got this frag, it had 3 heads on it. Its branching hammer so i stuck the stalk in the sand in an open area of my tank and left it alone for quite a while now. Since then its grown quite a bit. It is in the process of splitting into what looks like about 8 heads now, and looks really good. Today I moved some of my corals around as i just set up a wavemaker and it looked like a couple corals close to the hammer were closing up from being touched. When i pulled the hammer out of the sand, i noticed that the stalk had grown about 3" longer under the sand. the stalk was placed upright in the sand, and now its grown along the bottom glass so it has a bit of a curve to it.

I wanted to glue the stalk to some LR and let the hammer spread out, but now it would look funny as the stalk is like 5" long! is it going to continue to grow? can i cut it off a bit before i glue it to the rock? should i put it back in the sand and let it grow there? I didnt think that the stalk would grow the other direction like that.