It's a bit tricky to define a single "shape" for irregular galaxies. That's because, by definition, they lack the organized structure of spiral or elliptical galaxies.

Here's what we know about irregular galaxies:

* No spiral arms: They don't have the distinct spiral arms seen in spiral galaxies.

* No elliptical symmetry: They don't have the smooth, oval shape of elliptical galaxies.

* Often chaotic: They appear more haphazard and jumbled, often with irregular shapes and patches of bright and dark regions.

Examples:

* The Large and Small Magellanic Clouds: These are two irregular galaxies that are close neighbors to our Milky Way.

* NGC 4449: A dwarf irregular galaxy with a very disturbed appearance.

Possible causes of irregularity:

* Tidal interactions: Gravitational forces from nearby galaxies can disrupt the structure of a galaxy, giving it an irregular shape.

* Mergers: When two galaxies collide, they can merge into a chaotic, irregular structure.

* Other disruptions: Supernova explosions or strong winds from massive stars can also distort a galaxy's shape.

In short: There's no one specific shape for an irregular galaxy. They're characterized by their lack of organized structure and often exhibit chaotic, asymmetrical forms.