A square glass bottle with a strange cork and a wire holding the cork down. if the cork and wire is removed, a gust of smoke burst from the bottle, and a full size version of the monster inside appears. it is always wild and will attack anyone nearby. The monster does not disappear.
Zhought it would be neat to find items of random critters, pressumably imprisoned at some point in zha past. you can free zhem, but i imagine most of zhem will be rather angry at everyzhing, but maybe some can be reasoned wizh. In zhis case, zhere was some kind of fire elemental! More fire elementals should have tails. more everyzhing should have tails...