An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

This strange coral-looking specimen is actually a mushroom. The photo, “Beautiful Destroyer”, was taken in the Panamanian tropical rainforest where the mushroom produces nitrogen, an element vital to soil health. (Photo by Sarah A. Batterman)

A participant holds balloons before the Annual March against Homophobia and Transphobia in Havana, May 14, 2016. (Photo by Reuters/Stringer)

A man tries to catch a duck during a competition held as a part of the Dragon Boat Festival, known locally as “Peh Cun Festival”, on the Cisadane river in Tanggerang, Indonesia, Thursday, June 9, 2016. The event is celebrated every fifth day of the fifth month on the Chinese lunar calendar. (Photo by Tatan Syuflana/AP Photo)

The International Garden Photographer of the Year is one of the world’s premier competitions specialising in botanical photography. There are 11 main categories and numerous special awards including Young Garden Photographer of the Year, and the mobile-only category Gardens on the Go. Here: Winner, Wildflower Landscapes category. Alto Paraíso de Goiás, Goiás, Brazil. (Photo by Marcio Cabral/The Guardian)

Yeshiva School students briefly dance on Grant Street after the menorah lighting outside of the City-County Building for the fifth night of Hanukkah, Thursday, December 26, 2019, in downtown Pittsburgh. (Photo by Alexandra Wimley/Pittsburgh Post-Gazette via AP Photo)

This year’s World Nomad Games, a celebration of nomadic heritage, took place in the Issyk-Kul province of Kyrgyzstan. Eleanor Moseman photographed female competitors who had travelled from all over central Asia and eastern Europe, and explored the difficulties and challenges they face as competitors. (Photo by Eleanor Moseman/The Guardian)

With its huge eyes, comical name and diminutive size, Mark R. Smith’s image of a baby Hawaiian bobtail squid can’t help but raise a smile. A curiously endearing creature, the cephalopod is just 1.5cm across, its mantle cavity bearing more than a passing resemblance to a rather natty shower cap. But it is also a beautiful example of symbiosis – nature’s version of “I’ll scratch your back if you scratch mine” – for on the underside of the squid is a light organ which houses bioluminescent bacteria. The squid offers the bacteria protection and food, while the bacteria emit a glow – a handy trait that the squid uses to offset its silhouette, helping it to evade predators in the depths below. Mark R. Smith’s entry combines several images of a Hawaiian bobtail squid with different focus lengths to create a final picture with greater depth of field than normal. (Photo by Mark R. Smith/Wellcome Images/Macroscopic Solutions)