Haootia quadriformis is an extinct animal belonging to the Ediacaran biota. Estimated to be about 560 million years old, H. quadriformis is identified as a cnidarian polyp, and is regarded as the earliest animal possessing muscles. Discovered in 2008 from Newfoundland in eastern Canada, it was formally described in 2014. It is the first Ediacaran organism discovered to show fossil of muscle fibres. Structural comparison of the muscles and morphology indicate that the animal is a cnidarian, though, which class H. quadriformis belongs to is currently undetermined.