What Am I Riddles

Question: I move faster in certain solids, but slower in certain gases. I am typically broken by objects with large masses. I can be used as for pleasure, practice, and even an alarm. If used excessively, I can cause harm. What am I?

Question: My thickness is no more than a few centimeters, yet my depth can span to infinity. Although mundane, I intimidate most animals. When in my presence, you will inevitably follow me. What am I?

Question: You have forgotten us a long time ago! And you enjoy the lying show. Accept the greyness and live there. For our color, you don't care. Only as a child, you know That we live in a small world! Inside ...inside your childish soul.

Question: What is big, has 4 feet, and can fly?

Question: Tear one off and scratch my head. What once was red is black instead. What am I?