A robot sent to explore the submerged ruins of Japan's Fukushima nuclear plant is offering a new look at the damage from one of history's worst nuclear disasters. The device nicknamed "Little Sunfish" found melted clumps of material that could be the fuel debris it was sent to locate, according to updates Friday.

After an earthquake struck near Japan on March 11, 2011, a tsunami spurred by the quake hit the nuclear plant, damaging generators and causing three nuclear meltdowns and the subsequent release of radioactive material. No radiation-related deaths have been reported, but nearly 100,000 homes had to be evacuated in the aftermath of the disaster.

Six years later, the homes remain deserted. But underwater robots could be the key to decontaminating the area and making it habitable again. The Tokyo Electric Power Company (TEPCO), which owns the Fukushima nuclear plant, has been using robots mounted with cameras to explore the site, often losing them to radiation damage or challenging terrain. (See 360 footage of what’s left from Chernobyl, the worst nuclear power disaster in history.)

According to the Japan Times, the new robot failed to find the fuel on its first day of the operation on July 19 but offered the first look inside the unit 3 reactor since it failed in 2011. Video shows scattered debris and the factory’s remains submerged 20 feet under water.

Subsequent exploration of the reactor Friday revealed melted debris that may contain radioactive fuel. Previous attempts to find melted fuel at units 1 and 2 had not been successful.

Japanese company Toshiba has been heavily involved in the Fukushima decontamination process and designed the 11-inch-tall (30 cm) robot, which can rotate 180 degrees to record the full scope of the underwater ruins. It’s remotely controlled by four operators. “Little Sunfish” will continue its exploration over the weekend.

Once all the fuel is located, efforts to remove it and actively decontaminate the region are expected to begin after the 2020 Tokyo Olympics.