Sorry for your loss. It looks like either a clump of poop or lash egg material that has clogged up her vent. Could it have frozen to her vent? Do you feel like doing a necropsy on her, or shipping her to your state vet for a necropsy. If you do a home necropsy, take pictures of the organs and your findings to post for any opinions. Here is a list of poultry vets to contact for a necropsy: https://www.metzerfarms.com/PoultryLabs.cfm
Here is a necropsy where the organs are labeled for identification:
I’m pretty positive it wasn’t poop, there was tissue going back up inside. I’ll have to read about lash eggs. She was always wonky reproductively speaking. Ancona almost a year old, didn’t grow a comb until a couple
Months ago then it seemingly happened overnight she grew a comb and laid a tiny egg with no yolk. Then a normal egg, nothing in about a month but I thought it was just winter sort of thing. Then today I noticed that thing. It’s been 32 at night 40-50 during the day so I doubt freezing. Everyone else is healthy. I’m going to chalk it up to her just never being quite right.
Lash egg material is infection from salpingitis (inflammation of the oviduct.) Lash egg material may be laid or seen inside the abdomen or oviduct after death. It is the most common cause of death in hens. Sometimes the lash material can cause obstruction in the oviduct, similar to egg binding, but I have never seen a picture of something like your hen had. Here is some reading about lash eggs: https://thepoultrysite.com/disease-guide/salpingitis https://the-chicken-chick.com/salpingitis-lash-eggs-in-backyard/