The sailors discovered a huge green metal sphere in the middle of the ocean: when they pulled it out of the water, they were shocked to realize what it was 

The sea was calm that day. The sun reflected on the water, and the ship glided steadily across the smooth surface. The crew expected an ordinary watch — until something strange appeared on the horizon.

From the depths of the ocean rose a gigantic green sphere. It looked metallic, yet it was impossibly smooth and perfectly round in shape.

At first, the sailors thought it was a buoy or part of some research equipment lost during a storm. But the closer they got, the stronger the feeling of unease became.

— Is that… a mine? — whispered one of the sailors, gripping the railing tightly.

The captain lifted his binoculars, stared for a long time, and frowned. On the surface of the sphere were strange bumps — small nodes or raised dots. None of the instruments detected any radio signals, which made everyone even more nervous.

The crew prepared for the worst. Silence fell over the deck. Everyone exchanged uneasy looks — each hoping it was just debris, not something secret.

As they came closer, they noticed metal brackets on the sides and raised structures. One of the sailors dared to reach out with a hook and gently tapped the surface. A dull metallic sound echoed — something was inside.

The sailors were shocked when they discovered what it really was 
To be continued in the first comment 

Later, it turned out to be a fragment of experimental oceanographic equipment. Such spheres are used to study sea currents and deep-water movements.

Normally, they’re anchored and fitted with sensors. But a storm or a technical malfunction might have torn it loose — and now this “eye of the ocean” was drifting freely across the open sea.

However, one mystery remained. There were no markings or numbers on the shell — just smooth green metal, as if someone had deliberately made it anonymous.

The captain ordered the coordinates to be recorded and a report to be sent. But as the sailors later admitted, in that moment everyone had the same thought:
What if it wasn’t a scientific instrument at all — but something far more serious, something that would never appear in official reports?

The sea, as always, kept its secret.