The group, which collectively refers to itself as "The Most Famous Artist," is offering to provide monoliths on demand for $45,000.

The monoliths, which bemused observers for their resemblance to the evolution-shaping alien structures from 2001: A Space Odyssey and their habit of appearing suddenly in remote locations, turned out to be a viral marketing stunt for the artistic collective and its "monolith-as-a-service.com" website, according to the artists.

The art group, which writes posts on social media as though it were a single person, is now offering monoliths for sale with "authentic dimensions and museum-quality materials," delivered in four to six weeks with extensive proof of authenticity. By way of comparison, the alien creators of the 2001 monoliths never provided any proof of authenticity, unless you count the ghost of an astronaut randomly appearing to tell people that something wonderful was about to happen.

"The Most Famous Artist" posted several articles about the monoliths in Utah, Romania, and California on its Instagram page, building up the mystery of the installations before concluding with a picture of a masked artist building a monolith and the playful taunt, "You mean it wasn't aliens?" The group told several of its online followers that it was responsible for all of the structures.