Wildlife Spotting

"Shell" is approx 9 to 11mm long. It seems as though it could be a caterpillar of sorts that drags its house ("shell") around with it. These are often seen hanging from a ceiling, watering can spout, leaf or some such handy place by a silken thread. When disturbed it will swing side-to-side, approximating a hanging leaflet, but with a little too much 'energy' to be entirely accurate. In order to do a 180 turn, the caterpillar disappears into the 'shell' and simply comes out the other end and crawls off. It may extend to about 4 or 6mm from the 'shell' when moving, and then shrinks its body, dragging the 'shell' up to its head.