They have not been completely ossified, which the process by which they turn from cartilage to bone.
Skulls are softer and divided into more parts to assist with the birth process. Skulls that are pliable move through the birth canal more easily causing less stress on the infant and the mother.
The cartilages at the ends of bones act as a soft pliable cushion between the bones that form the joint. Bone on bone movement is very painful.
A fontanel is any membranous gap between the bones of the cranium in an infant or fetus. They are more commonly discussed as the "soft spots" in a infant's skull.
Anterior fontanel
Perspex (PMMA) is not a soft solid.
the bones of the skull aren't fused together yet because the head is still growing. this causes the middle area to still be soft
Radiation that penetrates only two inches into the brain of an adult will reach deeper into the brain of an child. Because children skulls are thinner than adults and their brains contain more absorptive fluid.
Soft, pliable, flexible.
Fontanelles, or "soft spots". These are features of the infant skull that have soft gaps between the cranial bones. They allow for rapid stretching and deformation, since the brain expands faster than the surrounding bone can grow.
clay
turn in the mask
soft you can bend and hard you can not