She was built in 1929 as Nancy Baker by Germaniawerft in Kiel, Germany, later renamed Mona, and subsequently acquired by the Navy as the Lone Star on 10 February 1941.

Renamed Moonstone and designated PYc-9, she was converted for U.S. Navy service in Jacksonville, Florida, and commissioned on 10 April 1941.

On her return at Balboa, Panama, in July 1943, cracks were discovered in the cylinder blocks of her engine, and she was sent north for repairs.

On 16 October 1943, off the mouth of Delaware's Indian River she collided with the destroyer USS Greer (DD-145) and sank immediately.

This article includes text from the public domain Dictionary of American Naval Fighting Ships.