What kind of "artifact" is the unmanned submersible captured by China Navy?

Unmanned underwater vehicle (Unmanned Underwater Vehicle) is an instrument that navigates underwater without driving and depends on remote control or automatic control. It mainly refers to an intelligent system that replaces divers or manned small submarines for high-risk underwater operations such as deep-sea exploration, lifesaving and mine clearance. Therefore, unmanned submersibles are also called "diving robots" or "underwater robots". Unmanned submersible can be divided into military and civilian according to its application fields. In the military field, unmanned submersible can be used as an unmanned combat platform weapon in a new concept weapon. In this sense, the role of unmanned submersibles is similar to that of drones.

20 16 12 15 an unidentified device was found in the relevant waters of the south China sea by a lifeboat of the China navy, which was an unmanned submersible of the United States.

After friendly consultations, China and the United States successfully completed the handover of unmanned submersibles in the relevant waters of the South China Sea at noon on February 20, 65438.