sealskin: a garment (as a jacket or coat or robe) made of sealskin
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
phenylketonuria: a genetic disorder of metabolism; lack of the enzyme needed to turn phenylalanine into tyrosine results in an accumulation of phenylalanine in the body fluids which causes various degrees of mental deficiency