Mermaid Party Centerpiece. Take any table to the magical world in the wide ocean blue with this colorful Mermaid Party Centerpiece. A must-have decoration for any mermaid birthday parties, this centerpiece is easy to put together and will help bring all your decorations together for a special day your birthday girl and guests will never want to forget. Self-adhesive tabs make this simple to set up! Paper. 9" x 10"