Fantastic - the nitroplast joining a pretty exclusive club there.

Bigelowii itself seems very interesting, even without this nitrogen fixing organelle, having two completely different phases to it's life - one in a weird dodecahedral calcareous shell and one without as a mobile flagellate. Apparently it can exist and reproduce in either form, and occasionally switch forms. It took scientists a long while to realize the two forms are actually the same species.