Someone figured out in the 1960s that meat processors can eek out a few more percent of profit from chickens, turkeys, pigs, and cows by scraping the bones 100% clean of meat. This is done by machines, not humans, by passing bones leftover after the initial cutting through a high pressure sieve. The paste you see in the picture above is the result.
There's more: because it's crawling with bacteria, it will be washed with ammonia... Then, because it tastes gross, it will be reflavored artificially. Then, because it is weirdly pink, it will be dyed with artificial color.
But, hey, at least it tastes good, right?
High five, America...
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http://www.huffingtonpost.com/2010/10/04/mechanically-separated-meat-chicken-mcnugget-photo_n_749893.html )