Bottarga is the whole egg sac of a fish — most prized from the grey (flathead) mullet, Mugil cephalus — that has been salted, pressed flat and air-dried into a firm, translucent block the colour of amber to deep brown, often sealed in a coat of beeswax. Sometimes called the caviar of the south or Mediterranean caviar, it is one of the Mediterranean's oldest luxuries: intensely briny, savoury and umami, with a nutty, faintly bitter, marine-waxy richness and a dense, slightly waxy bite. It is rarely eaten in chunks; instead it is shaved or grated paper-thin over hot pasta dressed with olive oil and garlic, scattered over raw vegetables, eggs and bean salads, or sliced thin onto bread — a little dissolving into a deep, lingering savour. The grey-mullet form (bottarga di muggine) is the costly delicacy; a cheaper, redder, more strongly flavoured version (bottarga di tonno) is made from bluefin tuna.