Finding a rare human artifact is supposed to be the best day ever, but for Echo the mermaid, it quickly turns into a massive argument. Echo is absolutely thrilled when she discovers a fascinating object dropped from the world above the waves. She cannot wait to show it off, until her bossy older sister, Crystal, swoops in and claims the treasure for herself. Echo is sick and tired of having to share everything, and she decides she is not going to back down this time. The underwater squabble escalates so much that their mother has to step in, forcing the two stubborn sisters to spend time together and work out their differences. This relatable chapter book dives deep into the turbulent waters of sibling rivalry. Young readers will completely understand the frustration of dealing with an older sibling, making this oceanic adventure both emotionally authentic and highly entertaining.