I think it's a fig leaf, which was common at the time. Btw, I do not know the origin of the photo.
Yep, further research into the Victorian era has led me to several discoveries:
1. There is a LOT of
hairy Victorian p0rn out there... and I mean a LOT...
2. There are certain overtones to a lot of Sandow's pictures that I hadn't noticed before...
3. He clearly shaves...
And yes, that is a fig leaf which was commonplace apparently, but how is he attaching it?!? Glue?