Tumbeloth

The Tumbeloths are a species of subterranean creatures native to Thra.

Biology
Tumbleoths resemble terrapins, though their emerald-like shells are able to extend tendrils that allow them to hang from the ceilings of caves and for rapid movement. They like shiny objects, which they store in their shell that opens similar to a terrestrial clam. They only open their shells to those that they bond with.

Due to their addiction to shiny objects, they are considered pests that steal offerings from the Crystal.

Source

 * Jim Hensons: The Power of the Dark Crystal 01 (2017)
 * Jim Hensons: The Power of the Dark Crystal 03 (2017)