Yes, a vacuum/radio tube, good point. Of course it's speculation at this stage but, yes maybe.
The Electra carried a number of spare bulbs/ tubes etc... But then again I guess most planes of that era did. And of course there's the Norwich City, fishing fleets, loran station and so on but, it doesn't look 'reef like'.
That said there could be some species of crustacean that is 'bulb/valve' shaped or, a hermit crab got lucky, you never know, anything is possible no matter how strange it may seem.