Tumbling Creek cavesnail
This aquatic cavesnail lives on the underside of rocks inside of caves. It is only found in a few places in the Tumbling Creek area of southern Missouri.
As with many troglobites, these tiny snails are extremely vulnerable once they are exposed to the surface world.
Although their numbers were believed to be in excess of 15,000 individuals at the time of their discovery, a recent survey found no more than about 40 individuals alive.