In 2003 samples of the Starchild Skull's bone were examined using a scanning electron microscope. Previous research had discovered that the bone was thinner and more durable than normal human bone, and when examined under magnification strange fibers were found embedded within the bone.
Although the fibers are present only inside the bone, mycologists were consulted in an attempt to identify them as a fungus or other organism. They reported that it did not appear to be a biological contamination. Nothing like this has ever been seen in any kind of bone. Speculation is that these fibers act like the steel reinforcing rods in concrete, but so far the Starchild Project has not been able to isolate the fibers for further testing.
An unclassified medical condition called "Morgellons Disease" has been suggested as the cause of the fibers, but the size, shape, and appearance of the fibers in the Starchild bone are completely unlike those linked to Morgellons.