A sea creature that lived 99 million years ago has been found preserved in amber in an ultra-rare finding.

The fossil, found in northern Myanmar, is the first ever known example of an ammonite to be trapped in amber – hardened tree resin.

Amber normally encases and immortalises forest-dwelling creatures as it captures them, renders them unable to escape and then hardens.

It is thought the amber, which is also home to various land-dwelling organisms, formed on a shell-riddled beach close to resin-producing trees.

The 33 mm long, 9.5 mm wide, 29 mm high chunk of amber hosts a range of different organisms from the world during the Cenomanian age.

Amber normally traps and immortalises forest-dwelling creatures as it starts life as tree sap which captures them, renders them unable to escape and then hardens. It is thought the amber, which is also home to various terrestrial organisms, formed on a shell-riddled beach close to resin-producing trees

Professor Wang Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) reported the find.

The plethora of organisms includes at least 40 individual animals, the study claims.

Of the terrestrial fauna found in the amber, mites are the most abundant.

The researchers write in the study: ‘Amber is fossilised tree resin, and inclusions usually comprise terrestrial and, rarely, aquatic organisms. Marine fossils are extremely rare in Cretaceous and Cenozoic ambers.’

But the menagerie also included spiders, millipedes, cockroaches, beetles, flies and wasps, most of which would have lived on the forest floor.

Of the marine fauna, in addition to the ammonite itself, sea snails and sea slaters are present. The slaters are like those living on the seashore today.

The researchers used X-ray micro-computed tomography (micro-CT) to obtain high-resolution three-dimensional images of the organisms.

They found that the ammonite is a juvenile Puzosia (Bhimaites) and its presence in the amber supports a late Albian-early Cenomanian age for the amber deposit.

This discovery represents a rare example of dating using amber inclusions.

Researchers found the outer shell of the ammonite was broken away and the entrance of the shell full of sand. The amber also contains additional sand

The researchers used X-ray micro-computed tomography (micro-CT) to obtain high-resolution three-dimensional images of the organisms

Researchers found the outer shell of the ammonite was broken away and the entrance of the shell full of sand. The amber also contains additional sand.

They add in their paper, published in the journal PNAS: ‘The incomplete preservation and lack of soft body of the ammonite and marine gastropods suggest that they were dead and underwent abrasion on the seashore before entombment.

‘It is most likely that the resin fell to the beach from coastal trees, picking up terrestrial arthropods and beach shells and, exceptionally, surviving the high-energy beach environment to be preserved as amber.’

Flying insects were living close to the trees and got trapped in the resin while it was still on the plant and before it fell to the ground., where it captured the washed up, and dead, marine creatures.

The fossil, found in northern Myanmar, is the first ever known example of an ammonite to be trapped in amber