The study used advanced neutron imaging techniques provided by the Science and Technology Facilities Council (STFC) ISIS Neutron and Muon Source research facility at Harwell in Oxfordshire.
This enabled them to scan the inside of a group of six sealed first millennium BC animal coffins from ancient Egyptian sites such as the Nile Delta. In doing this they were able to produce detailed images of their contents without damaging the containers or the materials inside them.
Neutron imaging is a process by which powerful beams of subatomic particles called neutrons are directed at materials so that scientific instruments can infer details about these materials based on the path that neutrons take through them.
It is more effective than X-ray imaging at seeing through metal and allowed the researchers to ‘unwrap’ the mummies and see organic remains through their bronze or leaded copper alloy containers.
This is the first time that STFC is aware of that neutron tomography has been used to look inside sealed metal animal coffins to see animal remains.
It has huge potential as a tool to help archaeologists analyse complex objects without causing any damage to them.
The imaging confirmed the coffins contained bones consistent with North African wall lizards which were wrapped in textile.
Animal mummification was common in ancient Egypt with some cases of people mummifying their pets to ensure their presence with them in the afterlife.
The lizards placed in these coffins were not pets but mummified as part of religious practices and beliefs that particularly thrived in the first millennium BC.
The lizards studied here are believed to have been linked with the cult of Egyptian creator and sun gods, such as Atum who was often depicted as a human-headed creature with a part-cobra part-eel body, as seen on two coffins the team analysed.
Dr Anna Fedrigo, Neutron Imaging Scientist at the ISIS Neutron and Muon Source and former STFC Marie Skłodowska-Curie Fellow, said: "Neutron imaging has many important applications in 21st century science.
"This study shows that it can also shed light on the inner structure of complex archaeological objects, including their manufacturing techniques and contents."
Dr Aurélia Masson‑Berghoff, Project Curator at the British Museum: "In the first millennium BC, lizards were commonly mummified in ancient Egypt, as were other reptiles, cats, dogs, falcons, ibises, shrews, fishes and more.
"Lizards, like snakes and eels, were particularly associated with ancient Egyptian solar and creator gods such as Atum, and perhaps in the case of Naukratis Amun-Ra Shena.
"With the help of neutron imaging, we have the potential to learn more about the ritual and votive practices surrounding these once impenetrable animal coffins, the ways they were made, used and displayed."