Dry fish and shrimp paste called Gkapi กะปิ

This concentrated product of finely ground fermented shrimps in sea salt has an even more compelling smell than its companion, fish sauce. There are vastly varying qualities, the odor differing accordingly. Many are undeniably foul-smelling, but there are a few brands that actually have a pleasant, albeit very powerful, roasted shrimp aroma. Many Westerners have unknowingly purchased gkapi because of its benign name, "shrimp paste," only to discover its true nature. Not having the faintest idea of what it is supposed to be like, some have tried to return the product, complaining to the store that it has rotted and spoiled.
Like fish sauce, gkapi is rich in protein and B vitamins. It is an essential ingredient in making chilli pastes and curry pastes. Just about every curry paste has a dab or two of gkapi in it. When pounded and blended in with an array of aromatic herbs and spices, its powerful smell dissipates and actually makes the entire concoction very fragrant. When cooked into food, a little bit of this concentrated paste adds a whole lot of delicious shrimp flavor. A favorite use for gkapi among Thai people is as the primary ingredient in a very pungent dipping sauce for raw or lightly blanched vegetables and fried fish, called nahm prik gkapi. Wrapped in a banana leaf and roasted over hot coals, it is then pounded in a mortar with chillies and garlic, followed by the addition of lime juice, fish sauce and sugar to constitute an intensely hot, shrimpy and limy sauce. Other ingredients may be added to make other nahm prik (chilli dipping sauces), such as tiny, bitter pea-eggplants; fried dried shrimp; cooked and chopped fresh shrimp; young green peppercorns; sour tamarind and roasted maengdah, a roachlike insect with a most unusual fragrance. Nahm prik sauces are definitely for hard-core Thai food lovers only.