http://www.oceanproaquatics.com/shop/blue-palm-lollypop-tunicate-nephtheis-fascicularis-p-19727.htmlIt is common for the Blue Palm to drop their heads both during transit, and within the aquarium. During this time, the tunicate will cover itself with a clear mucous. This is not an indication of poor health. Within a short time, it will blossom and form new flower like heads.
My guess is that this is their way of getting rid of toxins similar to sponges shedding their cells. But it is just a guess