A hatchling gemfrog's body covering is relatively delicate compared to that of the adult, made of a mineral much like that found in seashells. As the tadpole metamorphoses into a froglet, its skin grows hard and heavy until becomes limestone. The eggs of a gemfrog are laid in the shallow dips that form pools on the tops of the mountain karsts where these frogs live. The pools often contain several small organisms, including gemfrog hatchlings. The hatchlings require water to build up their tough outer skin, and can be seen eating away at the rock that holds these pools, making the pools even larger over time. Once their exoskeletons are fully-formed and their front legs grow in, the froglets wait for a large rainstorm to come through and fill up their puddle, after which they can roam freely on land. In order to allow their tiny exoskeleton to move, they must keep their inner membranes cool and wet.
Karst gemfrogs are named for the rocky environments in which they live, and for the rare stones they like to eat. Unlike most frogs, which have a semi-permeable skin membrane to allow them to breathe, gemfrogs have an extra layer made up of tiny crystals that forms a sort of exoskeleton. This exoskeleton is made up of tiny crystals of calcite, which fuse with other materials to become limestone as the frogs age. Other stones and crystals that the frogs consume may get added and develop into intricate forms and patterns used in mating displays. As long as the inner membrane below the hard covering is kept wet, the frogs can move about freely, but should they start to dry out, the grains tighten and form a stiff casing that encapsulates the frog. The gemfrogs have developed ways to use this feature to their advantage, as they can allow themselves to dry out and become indistinguishable from the rock around them. This can be a defence against predators or drought, as the frogs can remain like this for months and even years. When the rains return, the frogs become saturated and can move around once more. Because of their exoskeleton's composition, these frogs are highly vulnerable to strong acids.
Sprite art: Tekla | Description: PKGriffin