I have chicken bones after being boiled down to mush.
Can they be crushed? Then what can I use them for?
Depending on how long you cooked your bone broth, your chicken carcass still might have some flavor. After straining your first broth, add fresh water and more aromatics to the pot. Boil for a few more hours, and then blitz it with an immersion blender. Strain, yielding a thick creamy broth that makes a delicious bowl of ramen.
(Most of the actual bone meal will be strained out and can be added to your compost heap.)
Bone is not typically considered fit for human consumption. Cooked, they become dangerous. They are brittle and sharp and can puncture the intestines(source). Uncooked they become a pathogen risk, especially with chicken bones.
There was a time when people ate bone meal, presumably for calcium, but that is no longer considered a good practice. More reading about Bone meal from Wikipedia.
I started using the slow cooker to make chicken bone broth. I put the carcass with water in slow cooker on high till it comes to a low simmer then turn down to low and cook for about two days with an occasional stir. I remove the skin that has floated to the top, pour in a strainer over a bowl, when the broth has cooled put it in the fridge. I scrape the fat off the top the next day. For the bones and solids in the strainer...delicious!! The bones are so soft, soft like the bones in canned sardines. It's a delicacy for us. Bones, marrow, cartilage (collagen), bits of meat etc. I use every part of the chicken now, nothing goes to waste! The bones are soft with a wonderful very soft crunch, melt in your mouth texture.