I guess its possiblen that also the Nautilus is designed to look ike aporthole but...this is probably the thread you want on this subject:
http://www.rwg.cc/members/index.php?showtopic=4008
Perhaps the most prominent line in the Audemars Piguet collection is the Royal Oak, which was launched in 1972. The name is rooted in English history: it is said that Charles II, when pursued by Cromwell's army in 1651, took refuge in the hollow trunk of an oak.
Inspired by the story, the Royal Nayy between 1803 and 1914 christened three of its largest battleships "Royal Oak." Spurred by the rich historical heritage of the name, Audemars Piguet decided to commission a design from that rascal Gerald Genta that would be a worthy reflection of this proud heritage. The shape is derived from the shape of a porthole, with the bezel attached by eight hexagonal bolts made of white gold. Purists may note that the slots of the screws are, of course, always perfectly aligned to follow the curvature of the case.