Top: velocity-channel maps of ¹²CO (3–2) in the velocity range where two faint, elongated bubble-like features (dubbed the fish bowls) are discovered in the central regions of OH 231.8 (Sect. 4.5). Bottom: zero-order moment maps of ¹²CO (J = 3–2) integrated over the V_LSR = [−13:+77] km s⁻¹ range. The big ellipses represent the projection on the plane of the sky of the outer surface of the ellipsoids that represent the north (left) and south (middle) fish bowls. The small red and blue ellipses represent schematically the receeding and approaching vertex of the ellipsoids projected in the plane of the sky. In the right panel the continuum emission map is atop the ¹²CO (3–2) integrated map. The dashed line connects the centroids of the north and south fish bowls.