Very many fibers contained in an extruded filament formed by chaotic mixing. The imprints of the internal fibers are evident on the right where a portion of the filament was removed by cryogenic fracture.
References:

1. B. Gomillion, "Fiber Production with In-Situ Formation of Fibrillar Microstructures by Chaotic Mixing," Ph.D. Thesis, Clemson University, December 2000.

2. D. A. Zumbrunnen, "Smart Blending: A Means to Obtain Fibers and Plastic Products with Tailored Properties," Journal of The Textile Institute, Part 3, Vol. 91, pp. 92-104, 2000.