Gino Severini, "Dancer, Propeller, Sea"

Gino Severini, "Dancer = Propeller = Sea," 1915; © Artists Rights Society (ARS), New York; The Metropolitan Museum of Art, New York.

The Met points out that this Severini painting, completed just after the artist produced his manifesto, Plastic Analogies of Dynamism, is in the rare form of a diamond, "the only example [of this shape] in Severini's oeuvre." The photo of the painting on display is from a video created by a museum visitor in 2017. Oddly, many copies have been circulating with the image mistakenly rotated to make a standard rectangle, as seen below. The museum adds some background information:

Like other artists associated with Italian Futurism, Severini was fascinated by the interactions of movement and matter and the dynamic speeds of the modern world. In his manifesto [...] he describes the sensory and visual "analogies" that resonate across seemingly unrelated objects, from a dancing girl to a rushing express train to abstract forms.

Here, he uses the same shapes and colors to convey the movements of a dancer, a spinning airplane propeller, and the rolling sea. The painting's unusual diamond shape — the only example in Severini's oeuvre — enhances the disorienting effect of simultaneous motion.

Wrongly presented version of a diamond-shaped painting by Gino Severini.

Some copies of Propeller have also stated, in error, that the painting was formerly called "Sea = Dancer." In fact,"Sea = Dancer" is an entirely different work, created a year earlier, in 1914. The painting is currently located at the Guggenheim.

Gino Severini, "Sea = Dancer," 1914; Solomon R. Guggenheim Museum.