The Cubensis I grew on paper + MG soluble plant fertilizer where also very solid, and fairly hard to cut.
They also bruised enough that it looked like you could paint with them as a paint brush.
I have also noticed the high spore load, which I guess is also good.
Re-post for educational and illustrative purposes:
This is Cubensis Cambodian, spores direct to brown rice (not suggested), with a CaCO3 (calcium carbonate aka: chalk, lime) barrier.
It was very aggressive. The paper substrate, as above, is enriched with MG soluble
plant (more than plants) nutrients.
The fruit body sample I took images of was a test sample, you can see it's density when split.
I also put some CaCO3 chunks to 'plain' hydrated paper, which worked to some degree.
Edited by Ferather, 12 March 2019 - 09:04 AM.