Starchild

The Starchild Skull is a 900 year old bone skull found in Mexico in the 1930s. The Skull has been tested and examined by various medical and scientific experts since 1999, and no condition or deformity has yet been identified that can explain its wide variety of abnormal characteristics.

Tests Conducted Include:

• CAT Scan, which proved the Skull was not deformed by abnormal fusion of the cranial sutures (the bone plates of the Starchild Skull are not stuck together in a way that stopped the skull growing properly and changed its shape)
  
• X-Rays, which showed the bone of the Skull to be uniformly thinner than normal human bone, that it had no frontal sinuses, and that there was no fluid or other abnormality between the brain and the inside of the skull
  
• Scanning Electron Microscopy (SEM) Analysis, which discovered highly unusual microscopic fibers inside the bone of the Skull
  
• Expert Analysis of the physical structure of the bone, which identified the bone as much thinner and lighter than normal human bone, but also discovered that it is much stronger than human bone, a feature possibly related to the fibers in the bone
  
• DNA Analysis, which is preliminary and ongoing, but has already uncovered both human and non-human DNA in the sample, and left experts optimistic that further testing will provide enough evidence to prove the Skull is a new species

More information here.