No I don't because I haven't seen one yet. If it really exist then people should be aware if they can harm us or not.
There's a lot of things proven to exsist which we cannot see with our eyes. Gravity, oxygen, protons, electrons, the wind, voices....
Who knows what all the other life forms that could exsist out there even look like, if we are even capable of seeing them with our 3rd dimension human eyes.
