Green lip mussels. Green lip mussels (Perna canaliculus) in a colander. Mussels are bivalves which means that they have two shells which are hinged on one side. The shells must be split open, as here, before eating. Mussel meat contains a high percentage of vitamins, protein and minerals. If they are not cooked correctly, mussels can be a source of food poisoning. A colander is a perforated bowl for rinsing and straining foods.