Alien life form from the movie Slither is a strange little creature even among parasitoid types of aliens.
It looks like a dart and when it finds a suitable host it launches itself and penetrates the victim’s body. On Earth, of course, the first victims it meets are curious humans.
Once in a body it nests in the brain and takes over the host but does not completely erase his or her personality. The host’s body transforms into a squid-like creature and all kinds of slimy tentacles start to appear in unexpected places.
Two of these tentacles are especially important as this alien uses them to reproduce by impregnating other humans.
The impregnated humans develop a bear of an appetite and a taste for raw, rotten meat. Mmmm, yummy. And their bodies grow, or rather swell to gigantic proportions.
When they eventually explode hundreds of slugs are born. They are eager to jump into the mouth of everyone and everything that crosses their path turning the humans and wildlife alike, even the cuddly Bambi, into vicious zombies.
They are all connected to one another in a hive-brain fashion and eventually they merge with the slither’s body creating a huge creature which slowly consumes the whole planet.
When it is done this alien travels further on in the form of a dart-like interstellar traveler. No rest for the wicked!