Yep, that looks to be either Epiweb or EcoWeb (same material; name depends upon the origin - EU or US, respectively), which is a synthetic version of tree fern made from recycled PETE soda and water bottles.
Originally it was black in color, but later moved to a medium/dark brown.
That stuff, epiweb...ecorock...rockwool, always reminds me of the rough side of scrub sponges. Hardware departments also have material that looks similar, only thinner and more tightly woven. It's used as an abrasive. I've often wondered if it's the same material woven differently.
I've often wondered the same thing Junebug. My hubby always jokes that I shouldn't be buying this stuff from the specialist, I should just go and buy some from the cleaning section in the supermarket.
As for Epiweb/Ecoweb with orchids, when I first mounted some Dens on it I wasn't sure if I liked it... but now they are really getting their roots dug into it and I think they really do like it now they are getting attached.