This is one of the larger of the 10 smaller anchor stocks waiting to be displayed. This is a detail of the word Isis, that appears in high relief, on this anchor stock.
Isis, and Egyptian deity, was a name (among others) commonly used for ships during the Roman Era.
There was a very famous ship mentioned by the ancient author Lucian that was about 180 feet long, 45 feet wide (beam), and 45 feet deep.
In his book Πλοἶον ἢ Εὐχαί ("The Ship, or The Wishes") the sophist Lucian described the Isis when he saw it in Athens' seaport Piraeus:
I say, though, what a size that ship was! 180 feet long, the man said, and something over a quarter of that in width; and from deck to keel, the maximum depth, through the hold, 44 feet. And then the height of the mast, with its huge yard; and what a forestay it takes to hold it! And the lofty stern with its gradual curve, and its gilded beak, balanced at the other end by the long rising sweep of the prow, and the figures of her name-goddess, Isis, on either side. As to the other ornamental details, the paintings and the scarlet topsail, I was more struck by the anchors, and the capstans and windlasses, and the stern cabins. The crew was like a small army. And they were saying she carried as much corn as would feed every soul in Attica for a year. And all depends for its safety on one little old atomy of a man, who controls that great rudder with a mere broomstick of a tiller!
(Wikipedia Isis (ship)