Island Packet 485 leaking device, help to identify

[Bluewatercruise]

First post, thanks for your patience and excuse my ignorance.
I was crawling over an island packet today and notice this device leaking into the bilge. It is located on the forward aspect of the engine bay bulkhead. Aft of the fuel tank. Sitting only 300 mm below the saloon flooring.
The engine had been run before I got there, it wasn't actively leaking but after a couple of hours of engine running it had leaked a lot more. Clean salt water leak.
My guess is its an antisiphon valve or vent for the wet exhaust that maybe supposed to leak a bit when running. Am I close?
I'm talking about the green topped device with the large wingnut.
Any knowledge is appreciated. Stupidly I didn't watch it with the engine running nor read the label on the side.
Regards.

[Sailmonkey]

That's the seawater strainer. It should not be leaking. Good news though is that it's an easy rebuild.

[Bluewatercruise]

Wow, that was fast and very helpful. Thanks very much.