Biocellulose is made from bateria, FOSTEX bio dyna is hybrid biocell with synthetic microfibers, less degrading/rotting.
https://www.belmondobeauty.com/sheet-masks/view/what-is-bio-cellulose
What is Bio Cellulose
Bio cellulose (or microbial cellulose) is a natural fiber with a diameter of only 20 nanometers – 1000 times thinner than human hair. This superfine fiber is an eco-friendly, biodegradable alternative to fibers produced through commercial manufacturing processes.
http://www.fostexinternational.com/docs/products/TH-900.shtml
*"Biodyna diaphragm is made by Bio-cellulose fiber featuring low specific gravity, high Yang's modulus and high internal loss at the same time to achieve 2 times high propagation velocity and 5 times high rigidity against the conventional plastic film based driver unit.
http://www.head-fi.org/t/595683/fostex-th900-impressions-discussion-thread
->Headphone drivers:
Magnetic circuit: Magnetic repulsion system. The magnetic repulsion system gives the TH900 high sensitivity with wide dynamic
Diaphragm: BIODYNA. Fostex developed the diaphragm "BIODYNA" for headphone application by using bio-techology. BIODYNA diaphragm is made by bio-cellulose and high performance inorganic fiber admixture. The bio-cellulose is generated by acetobacter. It has extremely fine fiber and high purity compared to the plant fibre cellulose. As a result, use of [the] BIODYNA diaphragm achieves the high quality sound maintaining good balance within all frequency bands. It also gives [the] advantage of sound resolution at high frequencies.
CD3000's FULL BIOCELLULOSE rotting:
CD3000:
CD3000:
SA5000 Improved FULL synthetic nanocomposite:
FOSTEX Hybrid biocellulose with synthetic microfiber, less rotting than full biocell: