© WikiCrested bandfish
The mystery fish with a flat head was found near Murrays Beach Boat Ramp in Jervis Bay by Wreck Bay Council workers on Wednesday. Stumped at the find they took the species to Booderee National Park's main office for identification.
The species, identified as a crested bandfish, has only 30 occurrence records listed on the Atlas of Living Australia and is rarely photographed.
The species is thought to feed on squids. It has an ink sac for defence and large eyes to help it see in the dark of the deep ocean.
Park staff do not know how the fish found its way to Jervis Bay but are excited about the find nonetheless.
"What a find," they wrote in a Facebook post yesterday.
"It's so rare the image on Wikipedia is just a drawing."
They added that their photos have now been uploaded to Fishes of Australia.
The crested bandfish is not the only deep-sea creature to wash up this week.
On Sunday a woman and her husband stumbled upon the remains of a giant squid on a beach in South Africa.
The dead sea creature weighed more than 300kg and spanned four metres.
"Oh my word, seeing it at first really took my breath away," Adele Grosse told Live Science.
"Honestly, it looked like a majestic prehistoric animal."
Comment: This is the latest in a spate of rare, deep-sea dwelling creatures turning up in coastal areas around the world recently (since June the 7th), see in addition: