An amateur archaeologist has found an unprecedented collection of Stone Age hand axes among material collected at the bottom of the North Sea.

Jan Meulmeester of the Netherlands found 28 axes, possibly up to 100,000 years old, in marine sand and gravel scooped up by a British construction materials supplier.

He also found fragments of bones, teeth, tusks, and antlers from mammoths and other animals that had likely been butchered with the utensils.

Early humans used the stone tools for several purposes, much like today's Swiss army knives.

During ice-age periods of the Paleolithic era, which ended about 10,000 years ago, sea levels were lower and the North Sea was grassland hunting grounds.

The axes's discovery proves that artifacts from that ancient period remain exceptionally well preserved below the seafloor, experts say.