Is it a mermaid?

When Benjie and Bel find a strange creature on a tropical beach they know it's a dugong. But the dugong insists she is a beautiful mermaid and to prove it, she shows them her mermaid's tail and sings them a mermaid song. The children aren't convinced but they play with their new friend all the same. When it's time for her to go back to sea, there is one surprise left - could she be a mermaid after all?