This is part of the thigh bone (femur) of a large plant-eating dinosaur called Iguanodon, which lived 120 to 140 million years ago.
Large specimens grew up to 2.7 metres tall and were 11 metres long.
Iguanodon got its name because its teeth were similar in shape to those of a modern-day iguana lizard.
It was one of the first dinosaurs to be discovered and scientifically described, by Gideon Mantell (1790-1852).
This fossil was found in the Wealden Clay near Ashford.
You can see a whole Iguanodon skeleton (nicknamed Iggy) on display at Maidstone Museum.