It is a sight to make even the bravest of beachgoers feel a little wobbly. But this 4ft jellyfish washed up on the North Devon coast should not put anyone off dipping a toe in the water. Despite its size, the Rootmouth Jellyfish – also known as the Dustbin-lid – is more or less harmless, with a ‘very mild’ sting. The scientific name of the species is Rhizostoma octopus, because of its eight major tentacles. It is fairly common off Britain and often becomes stranded ashore by currents and winds.