The Creature On the Beach

Emily doesn't like things with too many legs, so I expect she won't like this:

But I did, because I found it rather interesting. It's undoubtedly a millipede: slow-moving herbivore (more usually known as ooh look what's that creepy crawly thing?) with two pairs of legs on each body segment, unlike the much faster-moving centipede which only has one pair. This picture is about actual size (unless you have a really, really big computer screen, in which case I don't want to frighten you).

Where did I come across this millipede? On the beach near Barrow-in-Furness in Cumbria.

Now all the information I can find about millipedes tells me they live in places with lots of plants that they can eat. The middle of a large tract of sand didn't seem a very millipede-friendly place. In fact, I was rather on the verge of rescuing this one and taking it to the nearby grass-covered sand dunes, when I noticed that she was not alone.

All over the beach were hundreds and hundreds of them, about a yard from each other in solitary millipediness, trotting amiably along on their many little legs, seemingly focused on a distant destination.

Where did they come from? How did they get there? Where were they going? Had I come across the millipede equivalent of a works outing to Blackpool?

If anyone has the answer, please tell me. I can't say it's been keeping me awake at night, but it would be good to know.