It sounds as if they are tiny flakes of rubber-like material.
Elastic response of rubber-like materials are often modeled based on the Mooney-Rivlin model.
The floor was of a white rubber-like material that yielded under their bare feet.
The tubes are made of Silastic, a rubber-like material that has long been in use in surgical implants.
Equivalently, relatively small triaxial stretch states can cause very high stresses to develop in a rubber-like material.
This phenomenon was recently also verified by experiment of fracture in rubber-like materials.
It is then dried to form an inelastic rubber-like material.
Before the year 2000 lasers only produced lower quality in rubber-like materials.
In these rubber-like materials, which had a rough structure, higher quality was impossible.
This had also an effect on the rubber-developers who, in order to stay competitive, developed new high quality rubber-like materials.