It was twitching

Jason had moved the sofa to retrieve something that had gone underneath and he called me over excitedly to observe some wriggling worm-like creature. I thought it might have been another flatworm or something related to a leech possibly. I scooped it up on the edge of a piece of paper for closer inspection.

Jason then explained that he had in fact whacked a small gecko thinking that it would dash off in time. Well it did indeed dash off but the poor thing left his twitching tail behind. No more tormenting geckos, Jason!