Massive stars are born in dense molecular clouds in the universe. As the nuclear furnace inside them begins to burn, they generate huge quantities of radiation which heats and ionizes the surrounding gases. The pressure and wind from the star forces these regions to expand.
This doesn't happen in a perfectly symmetrical manner, but instead, the expanding gases form clumps and bubbles. Some of the denser clumps may actually be the seeds for elongated structures astronomers now refer to as 'elephant trunks.' You've seen pictures of these elongated structures, like the famous Hubble Space Telescope image of the 'Pillars of Creation.'
Looking at this image it's easy to see the elephant trunk shapes. There is even a nebula called the Elephant Trunk Nebula.
Several papers have come out recently describing attempts to model this process using computer simulations. Search results from astro-ph at arXiv brings up some very interesting papers, if you're into stellar evolution...or circus animals.
And my favorite mixed metaphor and acronym paper of all time-
The Eagle here refers to the Eagle Nebula. EGGs are Evaporating Gaseous Globules, and the authors want to know if the EGGs are sterile or fertile, in other words, will stars be born here? C'mon, this is fun stuff!
All you really need to know is there are still no flying monkeys in space, but we now have elephant trunks. They come in all sizes and shapes. And what do astronomers find in these trunks?
The only thing cuter than baby elephants, baby stars.