A mysterious structure built on a barge docked in San Francisco Bay might be Google's floating data center or the firm's Glass Store under construction, according to media reports.

A report by CNET late last week says that the huge structure -- a four-story stack of shipping containers is found on Treasure Island located between San Francisco and Oakland.

Google does have a patent -- granted in 2009 -- for the floating data center concept where the facility on a ship relies on ocean currents for power and sea water to cool servers.

The Portland Herald also ran a report about a similar structure on a barge in the Portland Harbor recently, speculating that it might be Google's floating data center. The media report says that the barge in Portland is registered to the shell company connected to the Treasure Island operation named By and Large.

There's also speculation that the structure is Google's future Glass Store. According to a report by CBS in San Francisco, the media company claimed it has learned that Google is building a floating marketing center. "... a kind of giant Apple store, if you will -- but for Google Glass, the cutting-edge wearable computer the company has under development," the report says.

However, no reports out there suggest a formal link between the mysterious structure and the Internet search giant. Google hasn't responded to media inquiries related to floating data center either, according to those media reports.