Wildlife Spotting

That's even more interesting. Do you think this is a native species? Was there a source of moisture at this site?

There are a number of native land snails in California. In 2011, the US Fish and Wildlife Service proposed to list 29 mollusk species (land snails, aquatic snails, and slugs) under the Endangered Species Act. So far, I have not heard any information on the status of this proposal. The 29 species are endemic to Washington, Oregon, and northern California, so this one in the southern Sierra probably was not included. However, I do know that the California Department of Fish and Wildlife had several land snail species on their list of species of special concern.