Richard Gordon suggests the object on the Miles step is a bull’s hindquarter.
“In the light of the sacrificial scene on the altar of Flavius Aper (Poetovio), the interpretation as a bull’s hind-quarter rather than shoulder is to be preferred. The scene at Ostia is perfectly in keeping with other evidence suggest- ing that (junior) Mithraic grades fulfilled specific manual tasks within the cult, in the case of Miles, butchery of sacrificial animals.”
See:
Gordon, R. 2013c. “The Miles-frame in the Mitreo di Felicissimo and the practicalities of sacrifice.” Religio: Revue Pro Religionistiku 21, no.1: 33–38.
The most detailed publication on this monument seems to be Diamandis Triandaphyllos. „Nouveau relief rupestre de Mithra Tauroctone dans la région de Xanthi“, in: Pulpudeva. Semaines philippopolitaines de l’histoire et de la culture Thrace, (Supplementum 6), Sofia: St. Kliment Ohridski University Press 2008, pp. 159‒171. There is information about the "rediscovery" or rather reclassification of this monument (previously described as "the image of a warrior") in 1973, but no information about Bogdan Filov´s discovery. What is the source of this information?
The site was destroyed in the 5th century but some elements, including the benches, can still been seen.
Ale Fernandez
This is actually in San Giovanni al Timavo, a little way along from Duino itself.
If you are in the area you can take a guided tour of the temple and it's surrounding area. This tour is described in detail on this page:
http://www.duinotourism.it/index.php?option=com_k2&view=item&id=1212:il-mitreo&Itemid=7&lang=en
There is also much more info here: http://www.gssg.it/index.php?module=subjects&func=printpage&pageid=28&scope=all (in italian)
According to wikipedia, mithraists always preferred natural caves to building things or expanding existing things so probably this area, known as the Carso, or Karst, is perfect for the original construction and long term preservation of this kind of temple in caves. They must have jumped for joy when they heard there was a mysterious river that popped out of the ground. I can't think of a better place for a mithra temple :)
