This information was last updated in 2004. The Tudors have not changed, but our understanding of them might!
The stem and base of the object are part of the box given to the church by Sir Stephen. The box was removed from the top and made into a chalice, or communion cup, around 1559. You can see that the stem and base are elaborately decorated, whereas the bowl of the cup is very plain.
In the Roman Catholic religion those who take communion during mass eat bread which they believe is transformed into the body of Jesus. Some of this special bread is kept in a box to be taken to the sick and dying. In the past, only the priest drank holy wine from a small chalice.
By 1559, England was a Protestant country. In the Protestant religious service (called Holy Communion) everyone shares bread and wine, in memory of the Last Supper shared by Jesus and his followers. The small wine chalices had to be replaced by, or converted into, large trumpet-shaped ones for use by the whole congregation. As there was no use for Sir Stephen's box any more, it too was converted into a large chalice.
The chalice is made out silver which, in Tudor times, was also used to make coins. There were no banks or credit cards, so wealthy people and the church regarded silver objects as an asset that could be traded or melted down in times of need.