Bottarga is made from the roe of cefalo, or gray mullet which is salted, massaged to expel air pockets, then pressed and dried. It's a gourmet which dates back to ancient times.
People fished from almost existence and once they learned of this preservation technique, they extracted fish roe sacs, salted and dried them to produce a deeply savory pantry staple that's resistant to rot.
Bottarga is delicious to eat with butter on warm toasted bread. It is grated over almost any starch or grain, vegetables, salad, spaghetti or just on its own, sliced paper thin and seasoned with a little salt or soy sauce, a little lemon squeeze, and a touch of flavorful oil.