In heraldry, supporters are figures usually placed on either side of the shield and depicted holding it up. These figures may be real or imaginary animals, human figures, and in rare cases plants or inanimate objects. Often these can have local significance, such as the fisherman and the tin miner granted to Cornwall County Council, or a historical link, such as the lion of England and unicorn of Scotland in the two variations of the Coat of Arms of the United Kingdom. The arms of nutritionist John Boyd-Orr use two garbs (wheat sheaves) as supporters; the arms of the USS Donald Cook, missiles; the arms of the state of Rio Grande do Norte in Brazil, trees. Letters of the alphabet are used as supporters in the arms of Valencia, Spain.Human supporters can also be allegorical figures, or, more rarely, specifically named individuals.There is usually one supporter on each side of the shield, though there are some examples of single supporters placed behind the shield, and the arms of the Congo provide an extremely unusual example of supporters issuing from behind the shield. While such single supporters are generally eagles with one or two heads, there are other examples, including the cathedra in the case of some Canadian cathedrals. At the other extreme and even rarer, the Scottish chief Dundas of that Ilk had three supporters: two conventional red lions and the whole supported by a salamander. The coat of arms of Iceland even has four supporters.