Kapala
Human sacrifice  Symbols

See: Yarmulk/kippa, Zucchettos    Saturn hat

http://en.wikipedia.org/wiki/Kapala

Kali  In India and Tibet the skull cup is known as a Kapala, and is used in Buddhist tantric and Hindu tantric rituals. The skull does not belong to an enemy, and indeed the identity of the skull's original owner is not considered significant, as ritual purity in death has divested the human soul from its corporeal form. Hindu deities such as Kali are sometimes depicted holding a kapala full of human blood

A kapala (Sanskrit for “skull”) is made from a human skull used as a ritual implement (bowl) in both Hindu Tantra and Buddhist Tantra (Vajrayana). Especially in Tibet, they were often carved or elaborately mounted with precious metals and jewels.

The kapala is a sacred sculpted cup made from the top of a human skull frequently offered by Hindu and Buddhist worshipers to their fierce deities. A legacy of the ancient tradition of human sacrifice, the kapala is nowadays perceived as a dark but fascinating form of sculpture. Tibetan kapalas, in particular, feature impressive bas-relief artworks depicting religious figures and scenes, and are often adorned with semi-precious stones and silver-work. The elaborate carvings were handmade and the skull was soaked in water to soften the bone. In Tibet, skull cups are used at Buddhist altars to offer wrathful divinities either wine, which symbolizes blood, or dough cakes shaped as human eyes or ears. Through the force of tantric visualization based on meditation and deep philosophical study,  a sort of transubstantiation will occur and the wine will be transformed into the Wisdom Nectar, a liquid form of the enlightened mind of one or all the deities in the Celestial Palace of the Mandala. This is just one of the many uses of the kapala in Tibetan ritual culture. Some modern-day kapalas are still shaped like the top of a human skull, but they are made of brass and while they are adorned with artistic motifs, they aren’t nearly as fascinating as  genuine human skull cups. http://www.odditycentral.com/tag/kapala