MWC 922 is a star surrounded by a planetary nebula. Dubbed the Red Square Nebula due to its similarities to the Red Rectangle Nebula, the planetary nebula appears to be a nearly perfect square with a dark band around the equatorial regions. The nebula contains concentric rings, which are similar to those seen in the supernova SN 1987A.[133] MWC 922 itself is an FS Canis Majoris variable,[134] meaning that it is a Be star containing exceptionally bright hydrogen emission lines as well as select forbidden lines, likely due to the presence of a close binary.[135] East of Xi Serpentis is another planetary nebula, Abell 41, containing the binary star MT Serpentis at its center.