Was something written on them?

According to Kirkwood, Meteoric Astronomy, a substance like charred paper fell in Norway and other parts of northern Europe on Jan. 31, 1686. In the Annals of Philosophy, 16-68, the substance was described as “a mass of black leaves, having the appearance of burnt paper, but harder, and cohering, and brittle.”

–Charles Fort, The Book of the Damned, p.57 (The Complete Books of Charles Fort, Dover, c1974).