It's the skeleton of a type of cactus (Cylindriopuntia). It's used a fair bit in aquaria. It's especially used with freshwater shrimp as it is soft and they can pick it apart so I'm not sure how long it would last as a mount but it should certainly hold some water so could be useful for mounting an orchid in a low humidity environment!
It works very well for mounting. The mounts are attractive. The roots rap around and weave into the hollow core. The wood skeleton is quite hard and seems to hold up well. It comes in all sorts of sizes including very small for miniatures. I’ll post a photo on Monday
Chola mounts (as with most mounts) tend to dry quickly so it is pretty hard to overwater. Having said that, for me, two factors govern. Relative humidity in the location (mine tends high) and plant requirements. That barkeria and other similar types get water maybe 3x per week. If temps high I could water every day if need be.
I like to mount plants because the roots get lots of air and as we know ITS ALL ABOUT THE ROOTS.