This piece of gorgonian coral, bigger than the two men attempting to untangle it from their fishing nets, was more than 500 years old. It was destroyed by one of the most aggressive fishing practices ever used, known as bottom trawling, and was dumped afterwards by the New Zealand vessel which dragged it up. Bottom trawling involves large underwater nets up to 40 metres wide that are dragged along the sea floor. Huge chains or rollers attached to the front of the nets destroy everything in the their path, including coral forests, as well as sponges, sharks, giant crabs, boulder fields, and rocky reefs. This type of fishing is considered by scientists to be the greatest threat to deep sea biodiversity and results in high levels of incidentally caught species, known as bycatch.