Caspian Sea
The Caspian Sea, like the Black Sea, Namak Lake, and Lake Urmia, is a remnant of the ancient Paratethys Sea. It became landlocked about 5.5 million years ago due to tectonic uplift and a fall in sea level. During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like halite that were covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled the basin. (Comparable evaporite beds underlie the Mediterranean.) Due to the current inflow of fresh water, the Caspian Sea is a freshwater lake in its northern portions, and is most saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl embayment, which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10.
Cordylophora caspia
"C. caspia" is native to brackish and fresh water habitats around the Black Sea and Caspian Sea. From there it has spread, on the hulls of ships or by some other means, via channels and inland waterways to most of the temperate and tropical world. It arrived in the Baltic Sea in the early nineteenth century and spread rapidly to the estuaries and inland waterways of Western Europe, reaching Ireland by 1842. By 1885 it had made its way to Australia and by 1944 to Panama. It has not reached Antarctica.