What's a radula?
Well, here's a picture from the marvellous wikipedia:
Yes, it does look like a piece of wallpaper designed by William Morris's ghost, but in fact it's something altogether different and much commoner.
In fact, I'd imagine there were thousands and thousands of these within a just a few metres of you.
A radula is a mollusc's tooth.
No, wait, wait! They're incredible. Sometimes they're just used for scraping off bits of leaf, but there are all sorts of deep dark and dangerous things going on in the slimy world of the mollusc.
For instance, some sea snails excrete acid and use it, together with their radulae, to make holes in the shells of other molluscs so they can get at their innards.
Some others have a special radula which acts as a poisononed harpoon.
The ghost slug has extra-long razor-sharp radulae which it uses to devour earthworms.
And as for giant squid, ooh, they can chomp up more or less anything.
Ooh yes. Be afraid, be very afraid...
and be very very careful...
...there are hungry molluscs out there!
Spot the frippet: radula. Radulae are very small, and also inside the mouths of slugs and snails, so spotting them isn't easy. You may see trails like these, though,
which are scrape-marks from the less vicious sorts of molluscs.
Other than that, your best chance is watching a snail eating the algae on the walls of an aquarium. Or at a snail dentist.
If you can find one.
The word radula is the Late Latin word for a scraping iron, from the Latin rādere, to scrape.