I have lived most of my life in semi-arid regions so I'm always amazed with statements like "the antler was green".
Around here a shed will get green if it is dropped near or in a stream, but away from water they turn white.
Occasionally an antler that has been laying around for a few years will have lichen grown on it. Looks kind of neat, since the lichen can be yellow, orange, even blackish-grey.
Jennings, do you run across any bones at all? Typically I run across a few small skulls (deer, rodent, bird...) or backbones.