F-word From The Deep.

Hubris, thy name is humankind. We took off to the skies and amongst the stars before we truly explored our own planet. Who knows what lurks in the depths of the oceans, where the Sun's radiance has no power? I've caught a glimpse.
We were observing jellyfish near the Tonga Trench when our sonar caught a sound that will haunt me forever. It was as if an enormous alarm clock rang, followed by a crash and...voice, grumbling in a language unlike any human tongue known. Somehow, the word "fhtagn" that I caught, possessed the distinct quality of the F-word.