Tegnue

Tegnue are rock formations on the seabed of the Gulf of Venice in the northern Adriatic Sea, found at depths of 15 to 40 meters off the Veneto coast near Caorle, the Cavallino peninsula, Lido di Venezia and Chioggia. Sometimes called Adriatic coral reefs, they are built from a mix of hardened clastic sediment, carbonate precipitated from methane seepage, and organogenic rock formed by red calcareous algae, bryozoans and tube worms rather than tropical corals. Research published in 2017 traced their development to ancient river channels on the seafloor from the last glacial period, with sediments dating to about 9,000 years ago and hardening and colonization by these organisms beginning around 7,000 years ago.