Crypts can actually be attached to rock/wood just like Anubias and Ferns!!! I saw some Tropica ones the other week and was puzzled at what type of plant it was until I could see the label on one. It was a Wendtii Green and had taken very well to the bogwod it was cable tied to!!
I may try it one day in the future.
As poster say above. Nutrient rich substrate is a luxury but not a necessity. A lot of people dose water column only and have inert substrate
AC