Most people think that technology progresses from the simple to the complex, but in mechanical things, it's often the other way around. There are lots of examples of complicated astronomical functions, even pre-dating the invention of the mechanical clock. There's record of a chinese water clock with even more complicated functions. One of the earliest known mechanical clocks had separate dials for the (even retrograde) motions of various "travelers".

The most interesting part of the article is the speculation that this was an ordinary object, one of many such devices. It's entirely possible, because it was made of expensive metal, which would have been re-used when the device outlived it's usefulness. This one survived in a shipwreck.