I wonder whether anyone knows what this pattern is that I found on my north-facing window sills earlier this year (see Photo, right)? It looks like some kind of footprint and seems to come in two sizes. A few months on, it’s still there…
• The pattern was made by snails or slugs as they grazed on algae growing on the sills. Slugs and snails possess a set of tiny teeth embedded in a muscular, gristly structure which forms what is called the radula (see my images of radulae at http://chelifer.com/radula/). Muscular action drags the band of teeth over the…
