I am not sure what "AE" means, but might guess "Air Exhaust" or aeration. They were used to provide external venting for tanks of liquid (particularly volatile ones) within the hull.

Modeller Tone Source Shipyard Plans for HMS Acheron (1911) from the National Maritime Museum Grid Size 1 mm Scale 1/48 This fitting could doubtless be improved. It is difficult to tell if all fittings of the same size/function would be of the exact same design. It is so small that it probably was not rivetted in place. I do not know if the object was detachable/stowable, or if this feature would be outwardly apparent. This item would likely be painted steel, but that is Tone's guess.

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