Iolo Williams tracks down some of Wales’s most elusive creatures and sheds light on how some of them remain undetected. He begins by revealing the array of tiny creatures that take refuge in a log pile in winter: a hibernating butterfly, a centipede on the hunt and a dedicated earwig mother carefully tending to her eggs. Beneath the waves, marine animals are also hidden from view, but many also try their best to hide from each other. Sand gobies are well camouflaged against the seafloor but must be vigilant, as an angel shark, a rare creature filmed for the first time in UK waters, buries itself in the sand to ambush its prey from below.