Curly Maple
Curly maple is not a distinct species of maple but instead an anomaly in the grain that can be found in nearly all maple species. Called curly maple because the ripples in the grain pattern create a three dimensional effect that appears as if the grain has “curled” along the length of the board. This effect is often mistakenly said to be part of the grain of the wood; it is more accurately called "figure", as the distortion is perpendicular to the grain direction. Curly maple is known by several names some of which have distinct figure including flame, tiger, ripple and famously as fiddleback maple in reference to its historic use for the backs and sides of violins.
It is not completely clear what environmental conditions (if any) cause this phenomenon, but there are different grades of curly maple defined by its color, frequency and intensity which greatly affect its price.