The United States conducted the Baker nuclear test in 1946 to evaluate the effect of atomic weapons on warships at sea. Initially, the US was unaware of the extent of the radioactive contamination they had caused, so they asked Sailors to mop the ships in order to decontaminate them. However, Dr. Stafford Warren soon realized the gravity of the situation and pleaded with the Navy to evacuate. Unfortunately, the Geiger counters they had on site could not detect the main threat, plutonium, and the Navy saw no reason to abandon the cleanup. It took a week for Warren to convince everyone to leave, and he finally did so by demonstrating the shocking power of plutonium. He pulled a fish out of the ocean and threw it onto a photographic plate, where it was still alive and flapping around. The fish had absorbed so much plutonium that it took its own x-ray, known as an auto radiograph.