It's mentioned in the article. Mr Hutchings speculated that the monolith may have been installed by "some new wave artist", or a fan of 2001: A Space Odyssey,

It's mentioned in the article. Mr Hutchings speculated that the monolith may have been installed by "some new wave artist", or a fan of 2001: A Space Odyssey, the 1968 film directed by Stanley Kubrick.