Wading in knee-deep waters, that's exactly what she found: a tooth belonging to the now-extinct Otodus megalodon shark species.Growing to more than 66ft (20m) long, the species was not only the biggest shark in the world, but one of the largest fish ever to exist.Almost as soon as they received their gifts and finished their breakfasts on Christmas morning, they headed to the shores of nearby Calvert Cliffs with her husband Bruce, she told the BBC's US partner CBS News."She has always wanted to find a 'Meg', but for whatever reason, she spoke it into existence on Christmas morning," Mrs Sampson told CBS.The family took the tooth to the Calvert Marine Museum, whose paleontology department confirmed the shark's identity and congratulated the "future paleontologist" on Facebook."