What are they made of?
This looks like the strange "clots" I have seen on a few autopsy videos that are removed from veins.
Sad to watch
>decidual cast
Well, it was definitely NOT a decidual cast
"A decidual cast is a large, intact piece of tissue that you pass through your vagina in one solid piece. It happens when the thick mucus lining of the uterus, called the decidua, sheds in the near exact shape of your uterine cavity, creating a triangular “cast.”
The medical term that doctors use for this is membranous dysmenorrhea. It can happen when you’re having your period.
Doctors aren’t exactly sure what causes it. But they do believe it can be a sign of an ectopic pregnancy (a pregnancy that forms outside your uterus) or related to hormonal contraceptives with progesterone."
https://www.webmd.com/women/decidual-cast-what-is-it