Many of them contain projecting cornified plugs which may be squeezed out, leaving pit-like depressions.
"Essentials of Diseases of the Skin" by Henry Weightman Stelwagon
The cells of the neoplasm may undergo fatty degeneration, or they may become cornified.
"A System of Practical Medicine by American Authors, Vol. I" by Various
The number, configuration and arrangement of the two cornified areas on each hind limb are constant.
"North American Recent Soft-shelled Turtles (Family Trionychidae)" by Robert G. Webb