Zebra fish skin. Coloured scanning electron micrograph (SEM) of the folded surface of skin cells from a zebrafish (Danio rerio). The microscopic folds are called microplicae. The larger pattern is formed by the shapes of the skin cells. In a zebrafish, large areas of the skin are normally covered in bony scales. The microplicae are thought to reduce friction. Magnification: x1600 when printed 10cm wide