This contributes to the vessel's very low magnetic signature - vital for mine countermeasures operations.

Scientists have long known that the earth's magnetic field shows slight variations and that each ocean has a different magnetic signature.

Under a laser pulse, each electron fired out a package of light called a photon that carried a magnetic signature, known as 'spin'.

Recent research suggests that they also remember the unique magnetic signature of each part of a coastline.

This suggests that the lower part of the ocean crust contains a substantial magnetic signature.