Answer:
What body part is pronounced as one letter but written with three, only two different letters are used?
Maritime marauders
What is filled with air and sometimes a gas, tied to a string and often seen on your birthday?
Casper was a friendly one and Demi Moore made a clay pot with one.
What is seen in the water and in the sky? It is part of the rainbow and can be in your eye
What has a big mouth, yet never speaks?