At the launch of a ship the person naming the vessel, often referred to as it's godmother, or the shipyard, would present the vessel with a momento to celebrate the event. After the launch that person, or yard, would most likely never see the vessel ever again. I can recall one Japanese built bulk carrier I was mate on had been presented with a very expensive set of goblets at launch which mysteriously disappeared after I relieved the chief officer (who was temporarily standing in for the captain who whilst in port had gone home to attend a family bereavement). On his leaving the vessel upon the captain's return the captain came to me raving about what that person had done whilst he had been stand in Captain, such as adding boxes of very expensive chocolate to the stores order for his own consumption ( he never got to enjoy them as they somehow ended up in my cabin and very nice they were) but worse he had helped himself to those presentation goblets.
On another Danish built bulker the godmother was a well known Danish modern art sculptor and she had presented the ship with a framed original of one of her works, a very weird and frankly quite scary looking ceramic plate. The yard had fixed it to the bulkhead outside the lounge/bar entrance but after sailing and the yard guarantee staff leaving some months later, it was taken down and placed in a safe place. About a year later the ship was bound for a Danish port for discharge and word came that the godmother would probably visit the ship and expect to see her art work in place. Frantic search for the safe place where the piece had been put was carried out on board but no one could remember where that safe place was so they faced huge embarrassment if she turned up and her art work was not in place. Fortunately she decided not to hike through a steel works dirty stockpile to visit so the search was abandoned. Don't know if it was ever found.
I believe instead of presentation gifts all shell tankers had a framed example of the mollusc it was named after, bit embarrassing on a 300,000 tonner named after a 1 inch big mollusc!
Rgds
J.A.