Consider the Butterfly Nebula:
I would have thought “Double Jellyfish Nebula” more appropriate, but apparent Jellyfish Nebula was already taken and confusion would ensue.
Now consider the Ant Nebula:
Now consider the Black Widow Nebula:
Now consider NGC 3079:
Do y’all see any similarity in structure?
Yet this is a galaxy, not a stellar nebula. If the effects are related, they evidently debugged any scalability issues.
Now here’s a different question about the Rotten Egg nebula:
How did this one get to be so lopsided? All of the other nebulae that have any structure at all seem to be more or less evenly balanced, like Eta Carinae.
There doesn’t seem to be another star involved, so why such dramatic asymmetry?
Finally, there's this one (more pictures and links here):
Given the “splatter disc” or ring around the waist of several other nebulae, I suppose something like this was more or less inevitable, but why does the ejecta bunch up like that? Also, this is at the heart of a supernova, not an “ordinary” nova like the others. It could, however, be a relatively neat answer to the problem of planet formation.