What are suture lines in mollusks?

Question

so what are they and how do they end up on fossils?

Answer 1

Basically it's that curvy line on the mouth when the mollusk is closed. Normally when they die, they die with their mouths closed so when they make an imprint on a rock, you can see the suture line, which is like the boundary by the mouth... Scientists use them to also help classify what kind of mollusk it is =) Hope that wasn't too confusing.