This is another view of the same Trigonocarpus, this view showing the open end of the seed. Seeds of seed ferns - this was probably from Medullosa - had open ends to allow pollen to enter. It is thought they were fertilized by pollen when they dropped into the water although a few paleobiologists believe insects may have pollinated them through the opening. Also why were the seeds encased in a fruit like covering (like avocados)? To be consumed by creatures that lived in the shallow swamp water?