Here are a couple of clues:
The box once belonged to a woman who lived in Kent in the 6th or 7th century, and it was found in her grave.
When the excavator opened it he found a bundle of short woollen threads; you can see their remains on the left of the picture.
If you said ‘work box’, you could be right, but perhaps the threads are too short to use for sewing. Another name for this type of object is ‘relic box’ because some scholars think the threads were special to their owner.
At the moment, there are two relic boxes on display on the third floor of World Museum. One is in the Weston Discovery Centre and the other in the Ancient World Gallery, where you can also see the beautiful Kingston Brooch.