Danish scientist flipped over one thousand and one shapes (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

BOHR (Niels Bohr, Danish atomic physicist) reversed (flipped), containing (over . . .) M (Roman numeral for one thousand), then I (Roman numeral for one). Plural of rhombus = shape otherwise known as a diamond or lozenge.