First the hard object needed to be softened and pulled apart. This was done, following tests on small areas, by soaking the object in dilute hydrochloric acid. This produced a brown liquid containing particles of different sizes which were separated using sieves. The different parts were then studied under a microscope.

These studies revealed that the meal eaten by the producer of the stool had included cereal bran and other unidentified organic matter. This confirms other forms of evidence which suggest that diet at this time included meat, fish, shellfish, cereals, fruit and nuts. In addition, however, there were many eggs of intestinal parasites — gut worms of the types known as whip-worm (Trichuris) and maw-worm (Ascaris). These are only regularly found together in pig or man, and the form of this stool suggests that it was human.

Calculations, based on the number of eggs recovered, showed that the individual was infested with a small number of maw-worms and several hundred whip-worms. By today's standards this would be a heavy infection; although well within the limits of human tolerance, the individual almost certainly had stomach ache at times!

Eggs of parasitic worms:

above: Trichuris
below: Ascaris

For more information see: The Archaeology of York 14/4 Environment and Living Conditions at Two Anglo-Scandinavian Sites by A.R. Hall, H.K. Kenwood, D. Williams and J.R.A Greig with a note on the coprolite by A.K.G. Jones pp. 225–9.