Abstract: A fiber includes a base having a surface to be impacted by a fluid wave for propelling the fiber forward and a body having a trailing end connected to the base, a leading free end, and a spiral shape causing the fluid wave to rotate the fiber. A locking system causes the fiber to engage and hold at least one other fiber being propelled and rotated by the fluid wave. A process for producing three-dimensional, self-interlacing composites by mechanical polymerization with ultrasonic manipulation, includes placing the fibers and a mixing fluid in a form or mold. The fluid is subjected to ultrasonic manipulation in a mixing step, causing the fibers to be propelled, rotated and three-dimensionally engaged and held to one another.