IC 4406: A Seemingly Square Nebula . ... Credit Copyright: H. Bond ( STSci ), R. Ciardullo ( PSU ), WFPC2 , HST , NASA Explanation: How can a round star make a square nebula? ... IC 4406 is most probably cylindrical, with its square appearance the result of our vantage point in viewing the cylinder. Hot gas is known to be flowing out the ends of the cylinder, while filaments of dark dust and molecular gas lace the bounding walls. ... NASA Web Site Statements, Warnings, and Disclaimers . ...