Red bone marrow is where red and white blood cells are made and yellow bone marrow is mostly made of fat.
红骨髓是制造红细胞和白细胞的地方,而黄骨髓主要由脂肪构成。
Crash Course 解剖生理学篇
And yellow marrow stores energy as fat — if you happen to be a predatory animal, yellow bone marrow can be one of the best sources of calories you can find.