The upper left and lower right corners of a square are symmetrically carved out with two concave ellipses. The upper right and lower left corners of the same square are...
The upper left and lower right corners of a square are symmetrically carved out with two concave ellipses. The upper right and lower left corners of the same square are symmetrically carved out with two concave circles. The edges of the square gradually rise and fall with the concave carving. The concave circle and ellipse forms are painted yellow.