What do you call a fish without an eye?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

Using exactly three matchsticks, can you divide the area into two equal parts?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Can you replace the X (both small and big x) with the numbers between 1 to 19 such that all the rows of 3 numbers between X (big x) sum to 23?

What begins with T, ends with T, and has T in it?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?