Here are a couple of grown fibers...
Here's a darkfield closeup of single fiber illustrating longitudinal defects which may assist the grown process by providing a channel for transport of iron atoms from the base of the fiber to its growing tip.
With results from this work, Channon presented a paper* at the 64th annual meeting of The Meteoritical Society held at the Pontifical Gregorian University of Vatican City 10-14 September 2001. Mr. Visscher was a recipient of a student travel grant made possible by the generous support of the Barringer Crater Company, the Vatican Observatory, and the Meteoritical Society.