The Simmons Family Crest Piece A (シモンズ家の紋章の欠片Ａ Shimonzu-ka no monshō no kakera A ) is key item in Resident Evil 6.
The piece can be placed on a red door on its circular-shaped pedestal, along with 2 others, that will allow Ada to gain access.
It is found by Ada very soon after entering the underground cemetery. It is kept in a chest with a structurally-weak padlock that is easily shot off by any of Ada's firearms. After taking the piece from the chest, a gate will close and Ada will have to fight off several zombies before it will open again.