In Convexity against symmetry (both with white columns on black background and with black columns on white background) – displays made of convex asymmetric regions juxtaposed to concave symmetric regions – observerstend to perceive convex columns as foreground figures. Other conditions being equal (same area and balanced inclusion), figure-ground articulation exhibits the prevalence of convexity over symmetry. Composition – one of the last Kanizsa’s artworks – plays on the rivalry between symmetry and convexity. Microstructural variations generate relief surfaces that fill up the approximatively symmetric central zone of the canvas, giving rise to a perceptual and biological rarity: a form supported by several factors of figure-ground articulation (inclusion, symmetry, inner complexity) but not convexity of homogeneus lateral zones.