Pilot Bret Hutchings said the silver-colored metal monolith was seen sticking out of the ground in the middle of some red rock. He said the structure appeared to be 10-12 feet high and seemed to have been intentionally planted, rather than merely dumped out of an aircraft.
Hutchings said the scene was reminiscent of the black monolith from 1968 film 2001: A Space Odyssey.
The pilot said he suspects the monolith is the work of an artist rather than extra-terrestrial beings.
"I'm assuming it's some new wave artist or something or, you know, somebody that was a big  fan," Hutchings told KSL-TV.
The Department of Public Safety said an investigation into the object's origins is ongoing.
"It is illegal to install structures or art without authorization on federally managed public lands, no matter what planet you're from," the department said.