detail from late 12th c. manuscript leaf at the Art Institute of Chicago"[The Pope] holds the host with his left hand and points toward a chalice on the altar with his right. [...] A strange object, which appears to be a finger, rest on top of the chalice. Two sets of creases, visible underneath, mark its joints, and a fingernail has been delineated at the upper right."
--from "An Early Image of a Mass of St. Gregory and Devotion to the Holy Blood at Weingarten Abbey", Michael Heinlen, in
Gesta, Vol. 37, No. 1
St. Gregory (Pope Gregory I) was saying mass when a woman present started to laugh during
Communion, saying to a companion that she could not believe the bread was Christ, as she herself had baked it. Gregory prayed for a sign, and the host turned into a bleeding finger.
from The Sacred Shrine a Study of the Poetry and Art of the Catholic Church by Yrj Hirn, 1912
relic of the finger of thomas the apostle, rome, italy (my photo, taken 6/2009)