What powers a solar-powered snail?

[captpackrat]

http://www.theregister.co.uk/2008/07/03/dumb_science_exams/

I did a Google search for the phrase "solar powered snail", and found 446 hits.  Is this like a common item in the UK or something?

Comments

[harlequeen.livejournal.com]

http://www.bcfgardenspot.com/store-products-b5120-Solar-power-Snail-light_40874790.html

I've not seen a snail, but there are a variety of solar powered lights that pretty much fail to do anything of use.