"In 1996, we gave birth to a small monster which has since grown into the present system."
There was a very small monster that could fly.
However if it is use too much and can't be controlled, the user itself will become a small monsters as a side effect.
My job is to find plenty of smaller, weaker monsters for it to eat.
The mother is shown to be "much larger" than Dennis, the small monster.
The front door burst open and one of the smaller monsters came into the room, howling its terrible cry.
He constantly is making up games to throw around the small monsters as well.
Then there would be four to five hundred small monsters at large in the valley.
In this form his right arm has been replaced by a small, living, snake-like monster, which he could launch at the heroes.
Then the small supernatural monster began to disintegrate, but only so far as to become again a dense black cloud.