Short medium clean riddles for teens

I have all the knowledge you have. But I am small as your fist that your hands can hold me. Who am I?

What nuts give you a cold?

I have a face like a tree and skin like the sea. A great beast I am, yet small vermin frighten me. What am I?

A beggar's brother died, but the man who died had not brother. How could this be?

Give me food, and I will live. Give me water, and I will die. What am I?

Every night I'm told what to do, and each morning I do what i'm told. But I still don't escape your scold.

I live in the ocean. I have eight legs, two big claws and a tail. My body has a hard shell. I eat anything I can find. I am a...

Tall I am young, short I am old. While with life I glow, wind is my foe. What am I?

What do you call a cat crossed with a fish?

What time of day, when written in a capital letters, is the same forwards, backwards and upside down?