A shell fired from Serb positions in the hill exploded in the town centre on 11 August 1992, next to a building converted into a shelter for Bosniak women and children.
Researchers Allen Milligan and Francois Morel, of Princeton University, U.S.A., have found that silica in the diatom’s glass shell causes chemical changes in the water inside it, creating an ideal environment for photosynthesis.
Subsequent research found other differences, and it is now usually treated as a distinct species, probably more closely related to the Colorado pinyon P. edulis, which shares thin seed shells and needles mostly in pairs.
Nuclei with certain numbers of neutrons and protons (the magic numbers 2, 8, 20, 28, 50, 82, 126, ...) are particularly stable, because their shells are filled.