This is a remarkable and rare piece that we sourced from a very good antique auction house in Vienna. It seems to be 18th century, but could be early 19th.
It's a "todlein" (little death) or memento mori. These were used as devotional objects but also seemed to be popular simply as macabre objects. As ours is Austrian, we think it may also relate to the German sea-faring tradition of keeping dolls in tiny coffins as a good-luck talisman.
There has been debate about what these coffins may have been for beyond these uses - many of the theories are outlined in this article, "The Mystery of the Miniature Coffins" from the National Museums of Scotland (some similar coffins - believed possibly to be by Saxon/German makers were found in Scotland). You can also watch the fascinating video below.
It's beautifully made - the skeleton itself seems to be bone, and the coffin is lined with the type of metallic lace braid that was usually used in ecclesiastical pieces.
The skeleton figure is sealed in with a piece of clear glass - it's not open. This is a little hard to show on photos but if you need more pictures, please get in touch.
These pieces are very collectible now and not easy to find. This one is in excellent, antique condition.