Originally posted by Nerevar:

its the LEECHES

The concept literally depicts the other creature though. They even have the light-emitting organs (I forgot what they are called) found on the original creature, and the picture features the working title of the creature, which is not "leech".

Edit: The info is about this dev update: https://store.steampowered.com/news/app/892970/view/3673284490062877605?l=english