Under the ocean the ground began to shake in a minor quake, sand, mud and rock began to shift. When it was done, the ocean quake was hardly noticed by anyone. The only people who really noticed were a few researchers who had been monitoring seismograph but the quake was so minor it was quickly forgotten.
However, this quake would change the world and humanity forever, for when the ground settled an opening was relieved. This small opening lead down and down into a hidden world, this world was in truth an underground ocean cut off from the world for thousands of years.
Coming out of the opening in a rush was first a handful and then hundreds, then thousands of a type of parasitic fish which had never been seen before.
It was 2 to 3 meters long or 6.5 to 9.8 feet long with a wide mouth full of sharp needle like teeth. They were translucent to the point where one could actually see through them with the naked eye. All of them lacked eyes of any kind and some would say they looked like the back end of certain marine animals. Some looked like shark tails, some eels, some dolphins, some simple fish like and other stranger ones like octopus, lionfish and so on.
On the outside it made no sense, how could a creature like this come to be in nature.
This creature is in truth a parasitic creature
Researchers would soon find out that these creatures would latch onto a human and sink their fangs into their bodies, however they wouldn’t eat the humans. Instead, it would move around the humans hips and begin to fuse with the humans making what appears to be merpeople. The humans legs would be consumed even as they gained control over the creature giving them tails. They would begin to breathe through the creatures’ gills, as the translucent nature of the creature disappeared as scales or flesh began to change colors. The creature would also flood a human with other changes, be it making them physically different such as thinner, younger, or even whole gender changes.
These creatures turned in mass heading toward the shoreline where they sensed humans.