This small tin container is about 2.5 by 3 inches and 0.5 inches tall, and has a relatively mundane relief (typically a landscape) hammered into the hinged cover. Opening the container reveals that it is filled with 5-8 live, black leeches. Either removing a sufficient amount of leeches or reaching past them reveals that the  bottom of the container looks and feels like a rough stone wall despite being painted on.

The leeches will fully latch onto a suitable host after 1d4*5 minutes of being in contact of the skin.

At dawn, 1d6+1 leeches will emerge, rising out of the bottom of the container, to a maximum of 8. Leeches inside the container do not need to feed and are unharmed by environmental conditions.