Slug in disguise!

My husband spotted this wee chap making his way across our garden tonight, so he shouted on me...see he loves me really he knew I would want to take pictures of it!

It was all long, like a normal slug, at first and then one of my cats came over to investigate.

At first it just pulled its head inwards, then it did this.

It almost looks to me like it is pretending to be a snail, in an effort to ward off attack!