Some dinophytes, like Kryptoperidinium and Durinskia, have a diatom (heterokontophyte)-derived chloroplast. These chloroplasts are bounded by up to five membranes, (depending on whether the entire diatom endosymbiont is counted as the chloroplast, or just the red algal derived chloroplast inside it). The diatom endosymbiont has been reduced relatively little—it still retains its original mitochondria, and has endoplasmic reticulum, ribosomes, a nucleus, and of course, red algal derived chloroplasts—practically a complete cell, all inside the hosts endoplasmic reticulum lumen. However the diatom endosymbiont cant store its own food—its storage polysaccharide is found in granules in the dinophyte hosts cytoplasm instead. The diatom endosymbionts nucleus is present, but it probably cant be called a nucleomorph because it shows no sign of genome reduction, and might have even been expanded'. Diatoms have been engulfed by dinoflagellates at least three times.
The diatom endosymbiont is bounded by a single membrane, inside it are chloroplasts with four membranes. Like the diatom endosymbiont's diatom ancestor, the chloroplasts have triplet thylakoids and pyrenoids.
In some of these genera, the diatom endosymbionts chloroplasts arent the only chloroplasts in the dinophyte. The original three-membraned peridinin chloroplast is still around, converted to an eyespot.