What's this, and why was it clicking?

[Mk1Macca]

Ok, so yet another question while I learn my engine bay...

After the drive home, I thought i'd have a look under the bonnet while the engine was still running to check all the pipework. 2 things happened. One, I realised I didn't know what pipes to actually check (was looking for boost leaks), two, the box i'm pointing at in the below picture was making a very distinctive, and almost rapid 'clicking' noise.

So, a few questions I guess... What is this box, what does it do, is the clicking a bad thing, if so how do I fix it?

Also, I guess I should ask, which ones are the boost hoses, and what's the best way to check them! 

[Rhyso]

charcoal or EVAP canister

completely normal

[Mk1Macca]

I knew you'd know 

Thanks!

[tony k]

Dude, that bay could do with a detail.

[Mk1Macca]

That, to me, sounds like an offer!

The girls can talk babies...

[tg1]

whats the bit to the right of that? with the green cap/lid

[Rhyso]

whats the bit to the right of that? with the green cap/lid

Power steering reservoir

[Mk1Macca]

and what's the bit just below it with the blue cap, and what looks like a windscreen on it?













JOKE...