A tile used in table-top gaming. Dominoes were invented in China by the 13th century, but did not become popular in Europe until the early 18th century.
No default posture. No proper coloration.
Blazoned “a domino tincture marked (or spotted) tincture.”
Source: Pennsic Traceable Art 3. Artist unknown. Adapted by Mathghamhain Ua Ruadháin.