David Cook has been searching for the Stone for as many years as he can remember; what he finds is the Idol, David Archuleta.

Google’s Knowledge Graph is brand new — “only” containing an estimated 3.5 billion facts about 500 million objects — but of course it will grow as rapidly as the Googleplex can organize additional information. Even now it is a powerful tool for those who want quick answers, and don’t like wasting their time surfing to get them — loosely described as semantic search. For comparison, Wikipedia currently has less than 30 million pages.

Once Google has effectively tied its Knowledge Graph into its digitized library of almost every book on the planet and scraped the contents of the semantic web into its Googleplex, it will have a practical monopoly on access to many kinds of information .

"The fish use micro-electrode arrays to sense contaminants. In their current form they can detect phenols and heavy metals such as copper and lead, as well as monitor oxygen levels and salinity.

But the team has tried to build in flexibility.

Dr Speller explains: "We have designed it so you can pull out the chemical sensor unit, and put in different ones for something else, such as sulphates or phosphates, depending on the environment that you are monitoring," he explains.

One they've sniffed out a problem, the fish use artificial intelligence to hunt down the source of pollution.

They can work alone or in a team, communicating with each other using acoustic signals and they can continuously report back to the port.

"In the future, what I'd also like to see is not just a single task robot, but robots that can multitask - robots that can do search and rescue, monitoring for underwaters divers, at the same time as tracking pollution."