Answer:
What comes once in a minute, twice in a moment, but never in a thousand years?
I open wide and tight I shut, Sharp am I and paper-cut fingers too, so do take care, I'm good and bad, so best beware.
Different lights do make me strange, thus into different sizes I will change
The sun bakes them, the hand breaks them, the foot treads on them, and the mouth tastes them.
I'm full of holes, yet I'm full of water.
Those with eyes bigger than their stomach will definitely leave the restaurant with one of them. It is named after a house pet as well.