Battle Damaged Sci-fi Helmet - PBR by theblueturtle_, published under a Creative Commons Attribution-NonCommercial license
https://sketchfab.com/models/b81008d513954189a063ff901f7abfe4
The original model was built on an early draft of glTF 2.0 that did not become final. This new model has been imported and re-exported from Blender to bring it into alignment with the final release glTF 2.0 specification.