White matter is the slightly more pale tissue in the areas of the brain and spinal cord. It consists of nerve fibers with their myelin sheaths (the fatty substance that surrounds and "protects" the axon.
Water.
Sound travels slowly because the amount of pressure.
A bone cell, formed when an osteoblast becomes embedded in the matrix it has secreted.
Igneous. Igneous forms when lava cools off. :)
