I made roasted bone marrow once before, and it was delicious. Like a super tasty meaty jelly. This time, I ordered "marrow bones", but they were not the round cuts from the leg - these bones are flat, like part of a shoulder perhaps?
I found some that were "open" enough and roasted them like before, but this time the marrow was still hard.
The other bones were too thin, so now I threw all of them into a pot, to make a bone broth.
The only thing I did differently was that the bones were in salted water just overnight. Previously it was three days. But the marrow was also just different. So, did I do something wrong, or are they just wrong kind of bones?
The only bones i have ever seen the bone marrow come out of are the arms, the legs and possible the spine. Maybe other bones as well. I can usually break them and scrape the marrow out. It is quite fatty and stays together for me.
From the photos it looks like you were given a shoulder blade which wouldn't have any marrow in it.
I have used the marrow as a spread on sourdough bread. it was good!