On first glance they appear to simply be bland, bleach-white seashells, but when viewed under ultraviolet light they are transformed. Scientists have used a new technique to reconstrcut the colourful patterns on 28 fossilised cone snail shells that are up to 6.6 million years old. The technique has allowed researchers to look millions of years into the past to see how these once elaborately decorated shells would have once looked. The fossilised cone snail shells have bleached over time, like the one labelled A, but under ultraviolet light traces of pigment still in the shells are revealed, labelled B, allowing their colours to be reconstrcuted (C) Instead of being a simple white colour, they were infact covered in streaks of orange, purple, blue and even large pokadots. The scientists now believe the cone snail shells, which come from the northern Dominican Republic, include 13 entirely new species. A deadly tropical sea snail uses a super-potent form of insulin to subdue its fish prey, scientists have discovered. The geographic cone snail (Conus geographus) uses the chemical to cause a plunge in blood sugar, leaving the fish sluggish and unable to swim to safety. In this way the snail is able to entrap whole schools of small fish. C. geographus is one of the most venomous creatures on Earth, and known to have killed dozens of people in accidental encounters. It hunts in two ways, both by releasing toxins into the water and by firing a harpoon-like poison-tipped tooth into its prey.No antidote exists for a cone snail sting, which contains a mixture of nerve agents. The new research has uncovered one highly unusual ingredient in the cone snail's venom cocktail - weaponised insulin. In tests, a synthetic version of the hormone - made from shorter protein chains than normal insulin - lowered the blood sugar levels of adult zebrafish. Injected into water, it also reduced the movements of fish larvae. There are about 30 recorded instances of people being killed by cone snails, some of which have attractive and collectible shells. Dr Jonathan Hendricks, a paleontologist at the San Jose State University who led the research, said that the lack of colouration in many fosisilised cone snail shells made them difficult to identify. He said: 'Original coloration patterns — if not the actual colors themselves —sometimes become visible when fossil shells are illuminated with ultraviolet light, which causes formerly pigmented regions of the shell to fluoresce. 'Once a specimen has been photographed under UV light, it is possible to use photoediting software to reconstruct the original shell coloration pattern. 'This is done by creating a reversed, negative image, which causes bright, fluorescing markings to become darkened, corresponding with regions that were once pigmented.' Dr Hendricks used the ultraviolet technique to examine a range of fossilised shells that were discovered in the Cibao Valley of the northern Dominican Republic. Although it is now a rich and fertile inland valley, millions of years ago during the Neogene it was covered by ocean. All cone snails are venomous and predatory, with many species still around today. They use a harpoon like tooth that injects venom into their prey. In some cases the cone snail toxins are lethal to humans while many have a painful sting. Due to their bright colours and patterns they are often handled by unwary humans, leaving them vulnerable to stings. There are around 700 species of cone snail still living in tropical seas worldwide and around 1,000 species have been found in the fossil record. This image shows three of the fossil shells studied by the scientists as they currently appear without colour . Scientists used UV light to reveal tiny traces of the pigment left in the shell and the patterns they once had . However, identifying these can often be tricky as over time the bright pigments in the shells fade. Exposing them to ultraviolet light causes any remaining organic matter in the shells - like pigment - to fluoresce. It is thought that these compounds in the shells oxidise over time and so light up when UV light is shined on them. Dr Hendricks, whose work is published in the journal Public Library of Science One, compared the cone snail shells he examined with the patterns of those of modern Caribbean cone snails. He found that many of the fossils showed similar patterns, indicating that some modern species belong to lineages that have survived in the Caribbean for millions of years. UV light allowed scientists to peer back millions of years to reconstruct shell patterns and colours as above . Dr Hendricks said: 'This approach — combined with the exceptional Neogene fossil record of the Dominican Republic, as well as other regional fossil deposits — has the potential to provide a detailed understanding of the evolutionary and biogeographic development of the modern western Atlantic cone snail fauna. 'Clearly much more work needs to be done to better understand the compounds responsible for shell coloration. 'That said, it seems that oxidation - caused either naturally by exposure of shells to sunlight over prolonged periods of time, or artificially by soaking in bleach for several days - plays a role in causing formerly pigmented regions of fossil shells to fluoresce under UV light, though the reason is not currently understood.' C. geographus (above) is one of 700 existing cone snail species and is one of most venomous living animals .
Fossilised cone snail shells found in Cibao Valley of Dominican Republic .
In visible light they appear to be a plain white colour as the pigments faded .
Under ultraviolet light, however, the vivid patterns and colours fluoresce .
Scientists were able to reconstruct how the ancient species once looked .