Wikipedia
Guīlínggāo, also known as Tortoise Jelly (though not technically correct) or Turtle Jelly, is a jelly-like Chinese medicine, also sold as a dessert. It was traditionally made from the powdered plastron (bottom shell) from the turtle Cuora trifasciata (commonly known as "three-lined box turtle", or "golden coin turtle", 金錢龜) and a variety of herbal products, in particular, China roots Smilax glabra (土伏苓, Tu fu ling). Although the golden coin turtle (Cuora trifasciata) is commercially farmed in modern China, it is extremely expensive; therefore, even when turtle-derived ingredients are used in commercially available guīlínggāo, they come from other, more commonly available, turtle species.
More often, commercially available guīlínggāo sold as a dessert does not contain turtle shell powder at all, despite the product name and the prominent turtle images on most brands' labels. They do, however, share the same herbal additives as the medicine and are similarly marketed as being good for skin complexion when ingested.