tactoid

\\ˈtakˌtȯid\ noun (-s)

Etymology: International Scientific Vocabulary tact- (from Greek taktos, verbal of tassein, tattein to arrange, order) + -oid — more at tactics

: an elongated particle (as in vanadium pentoxide sol, tobacco mosaic virus, myosin, or fibrin) that appears as a spindle-shaped body under the polarizing microscope and occurs in a tactosol — compare coacervate