Spongy bone substance (6)
I believe the answer is:
marrow
(Other definitions for marrow that I've seen before include "It fills bone cavities" , "Bone filler" , "The best part" , "Connective tissue in bones" , "one of two" .)
I believe the answer is:
marrow
(Other definitions for marrow that I've seen before include "It fills bone cavities" , "Bone filler" , "The best part" , "Connective tissue in bones" , "one of two" .)