This is the aptly named Jellyfish Nebula. This nebula isn’t a standalone structure; rather, the Jellyfish is part of the much larger supernova remnant, IC 443. All together, the object is about 5,000 light years away and can be found in the constellation Gemini. The light from this magnificent event reached Earth about 30,000 years ago. A neutron star can be found within IC 443 and it is thought that this star is the core of the star that created the larger structure.
The Jellyfish itself can be found in the northeastern portion of IC 443. The bright star seen on the right side of the image is Eta Geminorum, which is one of the feet for Gemini.