[petuniasevan]

Not sure. Maybe nearby shock fronts (from supernovae) are a factor, or perhaps the star's spin rate influenced the direction of material ejected. Binary systems would produce weird nebulae too. Lots of planetary nebulae are strange-looking; astrophysicists are still studying the possible causes (that's scientist-speak for "we don't know").

[sleavelessinseattle]

The bubble guy in Seattle, who does parties for kids with soap solution and hoops and straws, can do square bubbles they're caused by the intersticial contact of precisely 6 bubbles and he inflates the contact point and when the little pocket gets big enough he takes a drag off a Highly PC Clove cigarette and blows smoke into the newly created pocket and sure enough...its SQUARE! more or less...If anyone came to FOLKLIFE...You'd KNOW these things!!! *beams...Next year! Memorial Day weekend...BE there or BE...