The ocean monuments from the Release 1.8 Minecraft update introduce 4 new blocks (prismarine, prismarine bricks, dark prismarine, and sea lantern), 2 new mobs (guardians and elder guardians), and 2 new items (prismarine shards, prismarine crystals). You can use these items to craft 3 of the 4 new blocks.
What is a natural levee and how is it made? -Natural Levees are formed by the river in its process of flooding -A natural levee is formed by a deposit of sand or mud built up along, and sloping away from, either side of the flood plain of a river or stream.
An analysis of historical cross sections showed that there was no natural levee along the riverbanks shortly after the regulation, about 100 years ago. We thus assume that natural levee formation is a consequence of the Danube regulation in the late 19th century.