These lenses are really useful in studying the animals’ age, because they contain a layer called the embryonic nucleus, which is made of proteins that are made during the earliest stages of the shark’s life.

这些透镜对于研究动物的年龄非常有用，因为它们包含一层称为胚核的层， 该层由鲨鱼生命早期阶段产生的蛋白质构成。