Escutcheon
An escutcheon is the shield that displays a coat of arms, the main part of the full achievement. A small shield set on top of a larger one is called an inescutcheon, or an escutcheon of pretence when a husband uses it for the arms of a wife who is an heiress.
Escutcheons come in many outlines. The heater shape, with straight sides and a pointed base, replaced the long Norman kite shield by about 1250. Women in English heraldry traditionally bore arms on a lozenge, a diamond shape, instead of a shield. The arms of Nova Scotia carry a small escutcheon of Scotland's royal arms in the middle of their saltire.
The coat of arms maker lets you pick the escutcheon on the Shield tab: Heater, French, Spanish, Swiss, Kite, Polish, Oval, Lozenge, Banner or Round. The shape never changes the blazon, so choose the one you like best. The parts of a coat of arms guide shows where the shield sits in the full display.