Pineal gland (also called the pineal body), from the Latin for pine cone, pinea; so named because of its shape.
The human pineal gland, 5-9 mm in length; drawing modified from www.hormone.org
Rene Descartes, the French philosopher, physiologist and mathematician, believed the pineal to be the seat of the "rational soul", impressed as he was with the gland's central location in the brain (indeed, it is one of few brain structures that does not come in bilateral pairs or equal left and right halves). 1,400 years earlier, the Greek physician Galen thought it served as a valve to regulate the release of thoughts from storage sites in the brain, which he assumed to be the ventricles. It's actual, less glamorous function is as a neuroendocrine source of the hormone melatonin.
Pineals can be easy to spot on radiographs as they often contain opaque deposits of "brain sand" composed of calcium phosphate and other salts. The material accumulates with age; significance unknown.
The piñata, commonly seen at Mexican birthday parties and other celebrations, also gets its name from the Latin pinea, albeit in a round-about way. Literally piñata means "pot", from the Italian pignatta, which in turn comes from the Italian word for pine cone, pigna, a direct descendant of pinea.