Here’s what you’ll learn when you read this story:

• Millions of tons of ammunition that remained unused after WWII was dumped off the coast of Germany. Now, these weapons of mass destruction have turned into entire ecosystems.
• Missiles, bombs and warheads are now populated by everything from fish and crabs to anemones, starfish, mussels, and bristleworms.
• Because some of these weapons have degraded significantly, scientists are suggesting they be replaced with other hard surfaces that are not leaking explosives.

Some of the most threatening things in the ocean aren’t even alive. Deep in the waters of Lübeck Bay in the Baltic Sea—between what are known as the Haffkrug and Pelzerhaken dumpsites—1.6 million tons of unused ammunition dumped (mostly) after World War II is slowly degrading. This seems ghastly, but just as nature was able to reclaim Chernobyl, it has found a way to make habitats out of explosive mines and warheads.

It would seem that missiles loaded with trinitrotoluene (otherwise known as TNT) are one of the most inhospitable places for life to take hold. But when exploring the undersea dump in 2024 (with an ROV lowered from the research vessel ALKOR), marine biologist Andrey Vedenin from the Senckenberg am Meer research institute in Hamburg, Germany, found an entire ecosystem thriving among what is essentially toxic waste. The graveyard of missiles, mines, torpedo heads, and bombs littering the seafloor was overgrown with algae and thriving with mussels, crabs, fish, starfish, and anemones.

“The majority of the epifauna was developed on the metal carcasses, on the transport parts, and the remaining shell of the warhead, as well as onfuse pockets if they were exposed,” Vedenin said in a study recently published in the journal Communications Earth & Environment.

While shipwrecks and slowly rotting piers have been known to be habitats for an entire menagerie of creatures—including the unmistakeable barnacles that stick themselves to boats and anything else floating around in the ocean for a long enough time—explosives are usually not an issue. What shocked Vedenin was that some of the fauna he observed actually preferred the surfaces of potentially lethal war relics to the surrounding rocks that have been there for hundreds of thousands of years. He thinks that life in the dumpsite may prefer the metal structures and other features of munitions as places to cling and hide.

Some of the most abundant species identified by the ROV include anemones, starfish, colonies of hydroid polyps, and bristleworms. The munitions they lived on were at varying stages of degradation, but how much of the metal had rusted away did not seem to have an effect on creatures living on the surface (except for anemones, which preferred more intact metal shells). There were, however, a few objects that had degraded enough to expose solid explosives covered in air bubble holes, which were devoid of life. Even the bristleworms avoided them.

While they don’t seem to concern the creatures living their best life on their surfaces, the weapons remain dangerous, as they contain dissolving explosives. TNT concentrations were far higher in the area than other regions of Lübeck Bay—or anywhere else in the Baltic, for that matter—and local fauna were exposed to different emission levels depending on which object they decided to populate.

Unfortunately, Lübeck Bay is hardly unique. Humans have turned oceans into a convenient dumping ground for more than unused missiles. Microplastics have taken over to the point that a species of amphipod with PET found in its stomach was officially named Eurythenes plasticus, and we are now ingesting fish and shrimp with a side of plastic. Explosives dumped decades ago are slowly dissolving into the ocean, and may eventually seep into something else that ends up on the menu (flounder and cod were among the fish found in the bay). Vedenin suggests replacing old munitions with safe objects, unless we would like our toxins battered and fried.

“Although adding new hard substrates to the marine ecosystems can be questionable due to altering the surrounding habitat,” he said, “in the particular case of the German Baltic Sea, new hard substrata can be a conservation tool and lead to conditions closer to initial natural conditions.”