That might be a condition of location or water quality, similar to how zoa's reach for light maybe they do too? I have seen them look like that though, in my biocube mine did that however when i moved them to my frag tank they look different.
Sometimes the vesicles just split like that, same with how hammers and torches sometimes split tentacles, even plate corals do it, I have a plate that is doing this aswell as another mushroom