Riddle me this:
I'm in a pillow, but not in a blanket;
In a piano, but not in a crotchet;
In a picnic, but not in a basket;
Close to four, but far from a quartet.
I'm not for treasure, but am for the pirate;
In a picture, but not in the camera;
I'm not for a plane, but am for the pilot;
How quickly can you pick up the answer?
The answer might serve useful for my previous puzzle.
You cannot put me on pizza,
But without me it would not exist;
Nonetheless, if you put margherita,
Instead of pineapple, then I will be missed.