Answer:
A mechanism to discover who is following you.
What is the middle of water but is not an island?
This patch of land stands alone
These are believed to be found at the end of rainbows
Deep, deep, do they go. Spreading out as they go. Never needing any air. They are sometimes as fine as hair
The more that there is of this, the less you see. What is it?
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?