"All female mer have them on there skin but they start small at first but then they add to for different reason like birth, death, marriage,etc . She wont have a full body one till shes my age so she will only have a small one at first then it will get bigger as she gets older it a type of spell that get bigger as we age. Cause my clan mark is originally on my stomach. But the spell is what makes each mer womans mark different