I saw a worm last night hanging out my rock. It was black with White stripe rings around it. I turned the light on to get a photo and it darted back on straight away, only to return as soon as the lights went off. I could only see the part that was hanging out, about 3inches long. Mainly black but definate thin yellowy White rings around it all the way up. I think it had a White head but may be making that up. It was just eating from a rock. Any idea?