Do you have rods in your head? I do.

The spars were there to support the sand mold cores. They poured Iron around the cores and the spars so your are probably still captive in the iron. They vibrate the sand cores loose and they fall out but the spars stay in there. If they are free to pull out, they probably rusted themselves free from the iron walls. Mine came out as if they were stuffed in there. My block and head was pretty rusty inside too, about a cup of sediment came out after the core plugs were removed and the drain was cleared.