Black canister under battery

There is a black canister mounted just behind the front bumper on the nearside, underneath where the battery sits. It has two rubber pipes, thin and thinner, running to the inlet manifold. I have never paid it much attention, assuming it was some kind of charcoal vapour absorber. But is it important? I was doing the routine clean of the throttle body, flame trap etc yesterday and on a whim I pulled off the rubber pipes and tried sucking/blowing. I can blow down the thicker pipe, but the thinner one appears blocked - I can suck a tiny bit and no more. Does this canister matter, for fuel economy or emisions? Are the pipes supposed to pass air freely, or is there a valve of some sort? I imagine that if they are supposed to be free, then a blockage will alter the air intake volume a little. On a similar subject now I remember, there is a much smaller version mounted just in front of the fuel tank. Is that important? Also, on the subject of mystery pipes, I have always been puzzled by the black convoluted plastic pipe that protrudes from the opening in the inner wing, just by the air intake. It is about an inch in diameter, with a conical cap on the end. I can't see where it runs to. Any thoughts anyone?

Hi Clifford, It sounds like the activated charcoal cannister which was in vogue some years ago there the eco fiends decided evaporating petrol would be best absorbed in an activated charcoal filter. The one on the tank sounds like more of the same. The under bonnet one was supposed to give up its adsorbed petrol and allow it back into the manifold to be burnt when the car was running. Regards, Checkpoint Charlie

Is it important? What happens if it gets blocked? Should it be changed or cleaned?