Uranium

Uranium is the 11th clue. It is an Ekat clue and was located in the Ekaterina stronghold in Bermuda Triangle.

History
The Ekats started a secret stronghold in the Bermuda Triangle. They guarded the clue so heavily, that it was thought that something mysterious was going on in the Bermuda Triangle because all planes that went into it, disappeared, when in actuality, it was the Ekats who were guarding their clue. Marie Curie, an Ekaterina scientist, discovered the clue and died because of it.

Uranium
Uranium is an element that is highly radioactive. Marie Curie, the discoverer of uranium, died because she did not know that it was radioactive at the time of its discovery.