I guess this goes under "Other cars" as I'd guess these blocks came out of former cars. I can't imagine how loud the noises coming out of this would be, in real life. Watch Shredder Tears Apart Engine Blocks Video | Break.com
Would there be any benefit to shredding aluminum and iron blocks separately? (I recognize that the post-shredding scraps can be separated magnetically.) Do you suppose that there is anything that can't be shredded?
You could freeze it in some liquid nitrogen for a few seconds and toss the bowl in. That would obliterate it.