Peduncle, a foot-stalk or tube on which anything is seated.
Pediform, foot-shaped.
Pelagic, belonging to the deep sea.
Pellicle, the skin or film.
Pellucid, transparent, clear, bright.
Pentagonal, having five angles.
Perforated, pierced with holes.
Pervious, admitting passage.
Phosphorescent, emitting light in the dark.
Pillar, in univalves is the internal continuation of the columella or inner lips, and extends from the base to the apex.