Apparently no-one knows when the shell grotto was built, who built it or why it was built. This, despite the fact that it took about 4.5 million shells to build it, so it seems as if it must have had some purpose and would have taken some time to build and create. The staff on the desk seemed rather frazzled when we first arrived, but once you are inside you can take as much time as you want. If you are likely to be frustrated by the lack of definitive answers, this isn't the place for you. However, if you would enjoy looking round what is something of a mystery, and let's face it, there aren't many of those around these days, and wondering about some of the possibilities that are suggested, then it's definitely worth a visit. I should say that the colouring of the shells has mostly faded, and the beauty and spectacle that remains, is based on the arrangements of the shells, and the sheer scale of the endeavour Some are just beautiful patterns, and others have been identified as specific shapes and are listed on your guide map. Despite having the map, I will confess to still not being able to recognise all of them, but some, like the turtle, are clearly identifiable.