Nightmare

This is supposed to be a nightmare. They lurk at night, seeking a young victom. You cannot see these with the naked eye, or with anything. When they find thier victom asleep, they use thier claws and tentacles to thear open thier forehead, then melt into thier brain.(all of this is painless) The wound heals with in a few minutes, and the nightmare begins its work.
When the child awakes in the morning (probably waking ater a few times) the nightmare evaporates into space, and waits till night, so it will strike again.
(I thought this up just after I scanned it in)