There are these little "bugs" that hide under the baseboard of my bathroom. They come out occasionally and crawl back really fast under the baseboard. These "bugs" are silvery-black in colour, they move very fast, and lately I've noticed little antennae sticking out of what looks like the head of the creature. It is also shaped somewhat like a tadpole and their size ranges from about 3mm to 9mm (to who knows what) in length. They have started to appear all around our house, and I wonder if the filling-in of our swimming pool had anything to do with it. My spouse almost caught one, but somehow squished it instead. Its exoskeleton turned to a grey shiny powder and the insides looked like something that came out of a boil.
We would really appreciate to know what it is and how to get rid of them.