The Crimson Pearl was an artifact seen in He-Man and the Masters of the Universe.
The Crimson Pearl was the only object on Eternia able to summon and control the sea demon Bakkull in a ceremony which could only be held once in every 20 years. This ceremony involved sacrificing a living being to the demon. The pearl itself was usually placed within the tip of a spear during this time.
Mer-Man attempted to use the pearl at least twice. The first time he had chosed a baby he had taken from Zoar's nest as sacrifice, but he was thwarted by Man-At-Arms. Twenty years later, he attempted to use Man-At-Arms adopted daughter Teela as the sacrifice, but this time his plans were stopped by He-Man.