Icacinicarya emarginata was a very small early Eocene icacinaceous plant known only from the inside of its fruit stone. The surviving fossils are locule casts — natural moulds of the seed cavity — rather than complete endocarps. They show that the fruit was only about 7 mm across and enclosed a nearly circular to subglobose seed cavity.

Fine papillae on the inner surface preserve useful reproductive anatomy, but the missing outer wall means the original external appearance of the fruit is unknown. No attached leaves or stems are known either, so the whole-plant growth form cannot be reconstructed from this fruit organ alone.