If a shell fills with sediment that later hardens, it forms an internal mold ( a 3-D picture of the space inside the shell). If an external mold later fills with sediment or minerals, it can form a ...

Commonly, fossil shells made of aragonite will recrystallize into a more stable form of the same ... Sugar can be seen undergoing the process of recrystalization in substances like old honey or maple ...

Scientists have found new evidence confirming that turtles once lived without shells. The almost-complete fossil dates back 228 million years and is bigger than a double bed. It was discovered in ...