The northern Adriatic Sea is transient, most recently flooded between 18,000 to 6,000 years ago following the last glacial maximum, and it will drain again with the onset of the next glacial period. Despite its youth, uniformly shallow depth, and flat sediment floor, it hosts a broad range of bottom-dwelling sea life ecologically resembling communities that have existed in the shallow sea since the Ordovician Period, some 500 million years ago...