P. pansa is distributed from Magdalena Bay in Baja, Mexico, to Peru. It is also found in the Galapagos Islands, Isla del Coco in Costa Rica and Isla Malpelo in Colombia.
The snail can be found on exposed rocky shores, between high and low tide lines. Often found in crevices.
These snails are predatory and feed on other mollusks.
Although once extremely abundant, the snail is becoming less common due to exploitation for dye.