Who built the ruins on Malden Island?

Malden Island is a tiny uninhabited dot of land sticking up smack in the middle of the Pacific Ocean, part of what is today the Republic of Kiribati. It was discovered by a British sea captain in 1825. And upon discovery of this tiny ~15 square-mile island, a mystery was born.

Specifically, the uninhabited island was the site of many stone structures, including the ruins of "temples" or at least monolithic, temple-like structures. Nobody knows who could have put them there. To this day, your theory is as good as anybody else's.

Very little else is known about or written about this site; however, I did find one crackling good conspiracy theorist who classifies it as 'forbidden archeology.'