Goob

Despite the goofy appearance, the gelatenous goo is a sentient alien creature which partially consumed its canine host before realising it was more useful alive. While it has selectively allowed for the lower jaw, eyes and brain to remain in tact (for various sensory purposes), any matter that touches it will most certainly be dissolved and 'eaten' by the goo. Still seems to retain some canid behaviour, though it's uncertain if that's to lure people into touching it and being consumed.