Sam, I don't see any actual Crossandra seeds in your photo. I just see the dried bracts.
You'll need to look for the seed pods within that dried stem of bracts. The pods look like elongated ovals with pointed tips. When the pods dry from green to tan, they will pop open explosively and distribute the seeds. The seeds are a straw color, have a rough texture, and are flat-ish (but not paper thin and flaky...more like a lentil.) Each pod will contain from 0 - 4 seeds. It can can be tricky to get the timing just right to catch the seeds. Collect them too soon and the seeds won't be viable: wait too long and the pods will spring open and fling the seeds to unknown places. I usually use a net bag over the whole flower spike when trying to catch seeds of Acanthus family (Acanthaceae) plants. They are tricky little guys!
I don't like to link to DG but it's all that I can find right now. The photo shows pods on the left and the actual seeds are shown in the lower right corner.
Edit: Oh, and explore the bracts gingerly. I recall getting some painful pricks from the dried bracts and such while looking for pods.
