Anyone remember the A Boat who adopted Philipp the duck in the Philippines, early 60's? I'm sure it made the Navy news or something similar as being the deepest diving duck in the world. A bathy dip to about 250' was carried out with Philipp aboard.
And on the first patrol for HMS Repulse Port Crew during her first commission, they apparently took a number of fertilised eggs on board (hens not Wrens!). One of thes eeggssubsequently hatched and was immediately christened "Fang".