Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
An iron ball, perfectly imbedded in the right ventricle of the heart, was found in a farm-butchered steer. The heart had been removed whole and set aside during the butcherIng. Placed in refrigeration, it was a number of days before the farmer was ready to use it. When preparing the heart for household use his knife struck something very hard. Cutting on around the center exposed a steel ball approximately two inches in diameter, neatly filling the right ventricle. The surrounding tissues had shaped themselves to the "embolus."
Casswell, D. L.
"The Case of the Cardiac Embolus (A true short story, a mystery),"
Iowa State University Veterinarian: Vol. 47
, Article 4.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol47/iss1/4