This image might be one of the most impressive photographs of all time. While it might just look like a regular Polaroid of some industrial sludge in a rundown warehouse, you’re looking at the epicenter of the Chernobyl nuclear disaster. Known as “the Elephant’s Foot of Chernobyl”, this cooled molten mess of radioactive material was once potent enough to kill any human that stood in its presence. While its power has subsided over the decades, it still emits heat and haunts the power plant’s ruins with dangerous levels of radiation. This monster was born in the Chernobyl disaster. Lurking in the depths of the reactor ruins, the monster is one of the most dangerous things in the world. In the immediate aftermath of the meltdown, spending 300 seconds in its presence would bring certain death. Even today, it radiates heat and death, though its power has weakened.

The Chernobyl disaster happened at 1:23 a.m. on April 26, 1986, when extremely hot nuclear fuel rods were lowered into cooling water, an immense amount of steam was created, which — because of the reactors’ design flaws — created more reactivity in the nuclear core of reactor number 4. The resultant power surge caused an immense explosion that detached the 1,000-ton plate covering the reactor core, releasing radiation into the atmosphere and cutting off the flow of coolant into the reactor. A few seconds later, a second explosion of even greater power than the first blew the reactor building apart and spewed burning graphite and other parts of the reactor core around the plant, starting a number of intense fires around the damaged reactor and reactor number 3, which was still operating at the time of the explosions.

After the nuclear fires were finally controlled, workers scrambled to contain the invisible dangers of the failed Chernobyl core. The concrete beneath the reactor was steaming hot, and was breached by solidified lava and spectacular unknown crystalline forms termed “chernobylites”. With the help of a remote camera, an intensely radioactive mass was found in the basement of Unit 4, more than two meters wide and weighing hundreds of tons, which they called “the Elephant’s Foot” for its wrinkled appearance.

The so called Elephant’s Foot is a solid mass made of melted nuclear fuel mixed with lots and lots of concrete, sand, and core sealing material that the fuel had melted through. It is located in a basement area under the original location of the core. In 1986 the radiation level on the ”Elephant’s Foot” was measured at 10,000 roentgens per hour, and anyone who approached would have received a fatal dose in under a minute. After just 30 seconds of exposure, dizziness and fatigue will find you a week later. Two minutes of exposure and the body cells will soon begin to hemorrhage; four minutes: vomiting, diarrhea, and fever. At 300 seconds you have two days to live.

In May of 1986, construction began on the sarcophagus—a gigantic concrete enclosure built to seal off the radiation from the outside world. But it’s not entirely sealed: the Chernobyl sarcophagus was outfitted with access points allowing researchers to observe the core and workers to enter. The contents of the Chernobyl tomb will remain radioactive for at least the next 100,000 years. All of the fire fighters and people who worked in building the sarcophagus died around a year or so after the event.

Why or how is there a man in the photograph standing right next to the Elephant’s Foot? The guy photographed with the radioactive slop is Artur Korneyev (sometimes translated as Korneev), a Kazakhstani nuclear inspector with a dark sense of humor who first came to Chernobyl shortly after the accident. Among others, he was tasked with the intimidating job of finding the rogue fuel and measuring radiation levels in the bowels of Chernobyl. The most famous image of him and the Elephant’s Foot (above) was taken in 1996, over 10 years after the initial disaster occurred. By this time, the Elephant’s Foot was emitting around 10 percent of the radiation it once had. These levels could still land a human with severe radiation sickness if they had close-up exposure for 5 or so minutes, however, it appears that a quick meter reading and a snap of the camera is not long enough to cause any dramatic acute health effects.

Why all the photos from the Chernobyl disaster appear grainy? This isn’t because the photography technology at the time in Soviet Union was behind. Previous photos are of better quality. It is because the radiation affects the film.

How were the photographs taken with the radiation at such high levels? From a safe distance, workers – or “liquidators” as they were called – rigged up a crude wheeled camera contraption and pushed it towards the Elephant’s Foot. Careful examination determined that it wasn’t all nuclear fuel. In fact, the mass consisted of only a small percentage of fuel; the rest was melted concrete, sand, and core shielding that all melted and flowed together. Over time, the Elephant’s Foot decomposed. It puffed dust and its surface cracked. But for years it remained too dangerous to approach.

Why is radiation dangerous? Particles emitted from radioactive atoms are a form of ionizing radiation—they have enough energy to scramble atoms and molecules they crash into. The reason that radiation can increase the risk of cancer is because destructive particles are playing a deadly game of red rover in our bodies. Our DNA is held in chromosomes—packets of billions of genetic building blocks holding hands in a chain, with astonishingly precise sequences. But radiation can break up the clasped hands, destroying or altering the bonds that hold DNA (and other important molecules) together. With enough damage to key components, cells start to function irregularly, leading to potentially lethal effects. For instance, the damage can make cells start reproducing uncontrollably, causing cancer.

How many people were eventually affected by the disaster? Over 7 million people were affected. The most heavily affected areas were in Belarus, Russia and Ukraine. However, sheep in northern England and reindeer in Lapland had to be killed as they had been irradiated.