Hmm good to know, I've been currious as to what they were for a while now. Finaly decided to ask! My first assumption had been that they were for restoring mana or something but quickly saw they did not.
Yea this is what happens for me as well. If I can crystal healing and a damaged monster walks over it, the monster is being healed when the crystals disappear. If this should be happening the other way then this i a bug, but I think it makes sense that whoever walks on the crystals is the one healed.
I think it's a testament to how deep and full of content this game is that I've seen people ask this question several times now. Kind of like how the other day I had no idea one of the mushrooms was used for alchemy, because I'd played 100 hours and yet never had a chance to try it out.