wanted : knowledge of stock air intake

i am the happy owner of a 1994 EX, for any of you who are fortunate enough to have owned one, or known someone who has, i have a question.

on the stock intake duct, between the block and the filter theree is a downwards facing tube that seems to contain some sort of diaphram, is this a stock bypass valve, if it isnt, then what the hell?

i have a 93 hatch and i think it's just a silencer of some sort cuz i took it off and the car is a lot louder now. the tube faces up in front of the motor and i don't know how any water would get in there anyhow. and i've heard that you would have to submerge the filter in water to "hydrolock". so i don't worry about it.