Similar to other sharks, dogfish have placoid scales, which are spiny and covered in an enamel-like substance. Sometimes referred to as dermal denticles because of their similarity to teeth, shark scales slant towards the tail end of the shark and reduce friction against water, making swimming easier. Sharkskin is so rough that it used to be utilized to polish wood, as sandpaper is used today. When the scales are removed, however, the skin can be cured and employed as leather.