I don't just mean the practical "it could hunt me down and maul me" danger of creatures like crocodiles, lions, tigers and bears. I mean something alien, like if you were hiking through the woods and saw a random new creature that you had never seen before. What kind of physical features would make this thing seem horrifying, like a monster that would make your heart drop and make you run like the wind? Instead of a reaction more like "Ooh, interesting, what kind of animal is that?" or "Huh, must be a unique local species." Again, something more unnatural and off-beat than the practical dangerous features of the predatory animals in our world that we know. If you came across a large bear in the woods, sure you'd be scared of getting hurt, but I'm looking for that extra level of "horror movie factor." A real-life bear would be scary if it entered your camping tent, but looking at Google Images of bears and reading about bears in nature books doesn't invoke fear. I'm looking for something where even its picture or video would make you feel creeped out. Know what I mean?