A rare sculpture by one of Germany's most important Surrealist artists, Max Ernst, is up for sale in an online auction. The rare art piece is expected to sell for $0.5m.

German painter and sculptor Max Ernst (2 April 1891 - 1 April 1976) is best remembered as one of the primary pioneers of the absurdist Dada movement.

This piece for sale is a patinated bronze sculpture with silvered and gilt details. The sculpture's base bears Ernst's signature, "Max Ernst," signed boldly.

Adding to the sculpture's general oddness is its affixed metal tag, engraved with title: "The Guardian of the Moon Fish". The artwork's overall dimensions are 10.25" wide x 8" deep x 20.25" in height.

Max Ernst's signed rare sculpture, 'The Guardian of the Moon Fish'

Ernst's sculpture depicts an abstract male figure - presumably "The Guardian" - whose head is inspired by African tribal masks. The figure's torso has a typically Dadaist nod towards the machine age, alongside bowed legs and spread-apart feet.

As you can see in the above picture, the figure is clutching the "Moon Fish", a silver and abstract crescent-form creature. Its tale is represented by a smaller gilt crescent.

Bids on this unique and rare Max Ernst art sculpture close tomorrow (February 4). It is selling in New York, although online bidding is available.

Previous high-profile Max Ernst auction sales include his painting A Maiden, a Widow and a Wife. Painted in Sedona, Arizona in 1956, the work brought £193,650 at Sotheby's in 2002 - and would no doubt be worth even more today.