This is a collection of unusual structures on the underside of a small sandstone overhang. It’s made of different material than the surrounding sandstone, it’s a hard to the touch with no visible sand grains. Most of the surface is made of tiny nodules that almost look like condensation on a cold surface. In the center is a more prominent raised area that looks like a cast of an animal burrow.
It’s located at the base of a gully near a creek, it looks like it goes through wetting and drying cycles as rain runoff flows and drys. I wonder if it could be the slow build up of minerals that are carried in the water then are deposited as it drys out.