Is the AtlasMesh under the following pathway a standard mesh structure? If so, what is it? Better yet, is there a way for those meshes in the AtlasMesh to be converted to a standard stl file or some other standard mesh file format? To be clear, I know the .gz is a compressed file;  I'm referring to the data within the text.

freesurfer -> average -> BrainstemSS -> atlas -> AtlasMesh.gz

I ask because I would like to use this this template as a target mesh for vertex analysis with the brainstem data I processed using freesurfer.