Space is full of peculiar shapes like ducks, guitars, speedboats or jellyfish.
When a massive star runs out of fuel and dies, there is a huge explosion called a supernova. The outer layers of the star are thrown off in all directions, while the core of the star collapses into a pulsar or black hole. After the explosion the outer layers of the star plough at great speed into gas surrounding the star and they begin to 'glow' in the radio spectrum. Now, ideally, you'd expect a supernova remnant to be nice and spherical. So this means that the weird shapes of supernova remnants reflect the complicated environment into which they expand.