By Seamus Duff The Masked Singer UK fans think they have figured out who is hiding under the piranha costume – with many convinced it is a former winner of The X Factor. The madcap guessing game is current airing its fifth season – with Piranha in the line up alongside a Dippy Egg, Eiffel Tower and Owl. The show has already uncovered three stars \- but viewers think they already known who is hiding beneath the razor tooth fish costume. Clues shared for Piranha so far state: “It’s pretty scary being underwater, other piranha’s snapping at you. I dream of getting away, with plenty of fish in the…