What goes up but never comes down?

One day Jenifer meets the Lion and the Tiger in the Forest of Forgetfulness. She knows that the Lion lies on Mondays, Tuesdays, and Wednesdays, and tells the truth on the other days of the week. The Tiger, on the other hand, lies on Thursdays, Fridays, and Saturdays, but tells the truth on the other days of the week. Now they make the following statements to Jenifer:

Lion: Yesterday was one of my lying days.

Tiger: Yesterday was one of my lying days too.

What day is it?

What happened when the wheel was invented?

Which fur should we be getting from the Lion?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

what does this picture(rebus) riddle means ?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

You can find some missing letters in the picture. By placing two particular letters in the spaces, you can form a nine lettered word beginning from one of the corners and going clockwise direction to the middle. Can you find out the letters and the word?