Hmm. Because they are sessile beasts that remain firmly attached to their substrate? Perhaps not. Maybe just because they are pretty:

We are slowly making our way around the world in a (mostly) anticlockwise fashion. The intention of this blog is to chronicle our adventures. Starting from Scotland we will make our way to Central America, then on to Australia and New Zealand, before enjoying a restful holiday in South East Asia.

You can look at our intended route here