Icacinicarya ovoidea was a small ovoid icacinaceous fruit with a comparatively sparse pattern of ridges and hollows. The hard stone enclosed an anatropous seed, and a marginal rib carried the funicular/vascular connection toward the apical placenta. Unlike several Iodes-like fruits, the lining of the seed cavity was not papillate.

Only locule casts of the London Clay species survive in the material assessed by the modern revision, so much of the original external wall is known from historical description rather than direct re-examination. The fossil nevertheless records more than a generic ‘seed’: it preserves the architecture of a one-seeded fruit, including the marginal attachment pathway and seed orientation. Its exact parent-plant growth form cannot be reconstructed from this organ alone.