THE world's oldest penis has been found in Herefordshire rock.

The 425million-year-old male member was discovered attached to a five-millimetre-long fossil of a rare sea creature at a top secret county location.

The cross between a shellfish and a prawn was given the Greek name Colymbosathon ecplecticos or 'amazing swimmer with large penis' by researchers soon after the find.

"The whole animal is amazing," said professor David Siveter of the University of Leicester, who led the study.

"Its basic body plan is very similar to living representatives. It has the same number of limbs, it has compound eyes, it has gills, it has a penis."

For fear of vandals attacks, the site will remain unknown as scientists continue looking for more groundbreaking results in the Silurian-age rocks, which are derived from volcanic ash.

The Herefordshire find pushes back the earliest described evidence for the soft-tissue anatomy by almost 200 million years.