Coal forms from the accumulation of plant debris, usually in a swamp environment. When plant debris dies and falls into the swamp the standing water of the swamp protects it from decay. Swamp waters are usually deficient in oxygen, which would react with the plant debris and cause it to decay.
Porokeratosis is generally considered to be a benign condition though malignant transformation has been seen in all but the punctate variety, necessitating regular followup of patients with porokeratosis (Maubec et al., 2005; Sasson & Krain, 1996).
Keratosis pilaris is a common skin condition that is often inherited and is characterized by the appearance of rough and small acne-like bumps. These bumps are usually white and most commonly found on the arms, thighs and buttocks. Keratosis pilaris usually affects young children, although it may occur at any age.