What is this?

THere is a box mounted under/outside the xj. Under the rear drivers side seat.

It has several hoses running to it.

I had one of my hoses fall off the other day and i could hear the sucking/ticking sound coming from it.

Just curious what it was and what would happen if some dirt or muddy water got sucked into it.

Thanks.

That is your EVAP cannister. It is charcoal filled and filters the gasoline fumes and feeds them up to the intake manifold. Probably not good to get water in it.

CANISTER, Vapor
4854 112 (EP0, Federal, California)