There's one that my Latin Teacher told me about called Garum: which is literally fermented fish. This was considered a condiment, and the product would be used by dipping or spreading over other foods.

What would happen is a fisherman would lay out his catch and shoppers would choose parts of the fish (usually the intestine). The parts would be left out for a couple of months to liquify. They would be covered in salt to make sure that decay didn't set in. A film would show up on the top and that would be used on other foods along with herbs and spices added to it.

Though it sounds gross it was apparently very nutritious.

I looked up a bit more and there's a book called "In defense of Garum" by Robert Curtis. though i wouldn't trust him haha.