Snail art?

Had my usual walk with Alison around Clumber lake this morning,the weather was lovely. It went down hill from there.
It's been pouring for the last few hours and I noticed a strange pattern on the back door, you can just about see it on the photo, but it looks a bit like a ghoulish figure!
I can only presume that the snails are out in force and are crawling around doing some snail dancing or something!!
I'm making a carrot cake for Mum's birthday tomorrow, I'll have to wait for it to finish cooking before I can go to bed.