The phrase "mysterious artifact" refers to an object that is old, unusual, or strange, and it carries an element of secrecy or unknown origins. Full definition
It can also be used as a third jump to reach those really high hanging mysterious artifacts when a double jump just won't do it. (iamericm.com)
Combining images photographed throughout my travels with my collection of mysterious artifacts, I painstakingly create my assemblages by welding, drilling, screwing, gluing, and sewing to create magnificent compositions. (artnyfair.com)
They must decipher encrypted clues, recover mysterious artifacts, and outwit their opponents to stay in play. (bookbrowse.com)