Not one to let “horrific” weather stop him, Craig Muir left his house in Hay-on-Wye in Powys, Wales, early Tuesday to take his usual walk up Hay Bluff when he spotted something large, shiny and new.

Standing there in the distance, like a beacon, was a silver monolith with no apparent trace as to how it got there or what it was doing in that spot.

It looked like it had “just been dropped down from space,” Mr. Muir said during a telephone interview on Tuesday. The sighting immediately captured media attention, calling to mind similar mysterious objects placed around the world in late 2020.

“It must be some sort of art installation,” he said. “If you didn’t know anything, to look at it, you could have easily thought it had been dropped off by a U.F.O. or something.”

Describing the location of the monolith as “the middle of nowhere,” Mr. Muir said there were no visible tracks, but he did see some footprints.

“I don’t know if someone else had seen it,” he said.