 A scale protects the body of the snake, aids it in locomotion, allows moisture to be retained within, alters the surface characteristics such as roughness to aid in camouflage, and in some cases even aids in prey capture (such as "Acrochordus").The simple or complex colouration patterns (which help in camouflage and anti-predator display) are a property of the underlying skin, but the folded nature of scaled skin allows bright skin to be concealed between scales then revealed in order to startle predators.Scales have been modified over time to serve other functions such as 'eyelash' fringes, and protective covers for the eyes with the most distinctive modification being the "rattle" of the North American rattlesnakes.