Why is my rabbit's poop jelly-like and not round? Is he sick?

Thanks for your question about Bugsy. The jelly like substance that you were seeing was likely mucous, and this usually comes from the colon when there has been a disruption in the way that the large intestine is moving. I am not sure if you can think of any diet changes that have occurred in the last week or so, or any stressful events - these are often the culprits of a one time jelly-like blob. The feces can also become a strange shape when this happens. If it only occurred the one time, I would just monitor Bugsy. If it continues, or if it happens again, I would recommend having him evaluated by a veterinarian as this may be indicative of him being sick. A rabbit's intestinal tract is very important, and something as simple as this is often an indicator of illness/disease.
I hope that this helps, and thanks for using Petco Pet Education Center, formerly Petcoach!