Your character gets up one morning and finds a little six year old girl sitting on the dock outside your house. When you approach her, she turns and looks up at you, completely silent, and you can see long white scars on her throat.
At the beach! She told the seashell her story, whispering every secret her memories held. Then she laid that shell at the ocean's edge and watched the tide pick it up and bring it out to sea. Hopefully, the mermaids will get her message.