Was looking at articles online and came across this which links the skull to Arcturius where the concept was conceived, before the time of Lemuria and Atlantis http://www.theskullwhisperers.com/id76.html:
Question to Metatron: There is a legend that speaks of there being 13 skulls, can you speak on that?
AAMetatron: Yes, 13, but only one holding the full energy of the 12. So then were there manifested 12 that represented each of the 12 singular aspects of the one, and so the 12 surrounding the one in the center, became in time a ceremonial and symbolic observance. Each one of the 12 then represented an aspect and an expression of each of the 12 dimensions of the earth plane, and each of the 12 division of each integral dimension, each strand of DNA, each component of the 144 that is so critical to the Earth experience, the Earth Plane. So then yes, each of the 12 is one twelfth of the one, the one containing the whole. In that way there are 13, and this was recognized by mankind in LeMuria, and later in Atlantis, OG, Egypt and Yucatan.
But again we wish to be clear, the 13 is the one whole and the 12 parts of the whole. And the one is the carrier of the human paradigm, and that pattern is imbued within the Divine Mind of all mankind, as the soul is imprinted with it entering this experience.
The 13 Crystal Skulls are produced originally by the process of Morphocrystallic Manifestation, involving the Pleadeans and Arcturians with imbuement of frequency to include the human genetic print from the Masters of Orion. These are indeed your true extra terrestrial lineage, and the crystal skulls are the frequential record of same.
Extra Terrestrial Origin
Question to Metatron: And so the skulls were original from Arcturius?
AA Metatron: Better to say they were creatively conceived in Arcturius. There the concept of the earth human experience was created and nurtured. We tell you that all humans have an experience of Arcturius, and it is a realm of great creativity, a playground, in your vernacular, of all creativity. You will be surprised to know that much of your creativity even as humans on the Earth, comes from an aspect of yourself that is tuned into the field, the frequency of Arcturius. It is where man becomes creative. For instance those you consider artistic; where are they when they drift into inspiration and are not in their body, we tell you that many of them are in Arcturius. Many of them are , interestingly , expressing the creativity in Arcturius. Is that not provocative?