Did she turn blue from holding her breath to long? This Limited Edition item was available for 350 MC from May 27-June 4, 2010 and gave 1 xp when bought. The description reads "Wish I could be.."
When clicked the mermaid runs her hand through her hair. Note: The Mermaid only sits on the rock and does not swim in water
Note: For the Mermaid that gives you quests see the Quest page.