The photographs feature fish that have been specially treated to make the stained skeletal tissues visible through the skin and flesh. The technique, developed by Dr. Adam Summers, uses dyes, hydrogen peroxide, a digestive enzyme and glycerin to make the flesh seem to disappear. Photo: This image of the butterfly ray (Gymnura crebripunctata) helped scientists study the joints in its wings. (Photo by Adam Summers)

A Santa hangs down the facade of the Hospital Germans Trias i Pujol, with the help of the Charity Firemen of Barcelona, as he visits children admitted to the medical center, in Barcelona, Spain, 19 December 2022. (Photo by Alejandro Garcia/EPA/EFE)

A woman is arrested during a mass gathering protest organised by the group called “UK Freedom Movement”, in Hyde Park in London as the country is in lockdown to help stop the spread of coronavirus, Saturday, May 16, 2020. The group claims that the coronavirus lockdown is illegal. (Photo by Kirsty Wigglesworth/AP Photo)

Two orphaned wallaby joeys enjoy a play date to help them boost their social skills in Australia early July 2023. The rescued joeys are being hand-raised at Aussie Ark in News South Wales. (Photo by Aussie Ark/Cover Images)

A woman wearing a face mask to help curb the spread of the coronavirus stretches her body next to a masked woman sitting on a bench outside a shopping mall in Beijing, Thursday, October 21, 2021. (Photo by Andy Wong/AP Photo)

Deaf and hard of hearing people perform a Buddhist Guanyin Thousand Hand dance to mark Sunday's National Day for Helping the Disabled in Yunnan, Kunming province, China on May 19, 2018. (Photo by Wong Campion/Reuters)

Drunk fresher is helped by students as she falls to the ground on night out at during the alcohol-fuelled Freshers’ Week in Birmingham, United Kingdom on September 18, 2017. Freshers are inducted during Freshers' Week – the first week of the Academic year – one of the busiest and most fun weeks of the year. (Photo by Caters News Agency)

A horse named Quinn, with a skeleton painted on it to help educate officers, is pictured during a visit by Britain's Queen Elizabeth II (unseen) and Britain's Prince Charles, Prince of Wales (unseen) to the Household Cavalry Mounted Regiment at the Hyde Park Barracks in west London on October 24, 2017. (Photo by Chris Jackson/AFP Photo)