Oyster Thief Phaeophyta
This odd-looking seaweed—which is about the size and more or less the shape of a tennis ball—is not a native species. It came first to France, arriving with the cultivated Pacific oyster, then made its way to the south coast of England. Despite being a foreign introduction, it’s never caused any problems, just the little buzz of joy in seeing something so peculiar bobbing about in the sea. And the common name? Well, it sometimes grows on oysters. When it gets to a certain size, its oxygenfilled body is sufficiently buoyant to lift the unfortunate oyster from the seabed and float off with it.