That's a seed pod.
Remy

How exciting, A Bee Pod!

If you don't want to mess with growing seed, you can cut the stem any time and discard the pod.

If you would like the adventure of raising children ( won't be true to parents ), you should watch the pod daily and when it turns white and starts to crack open, remove it dry the seeds and start it later this fall.

In any case, don't let the seed fall in the area of your current plant, because you won't be sure of your named iris rhizomes when you dig them and share them later.

Kristee

I'm not sure what all of mine are anymore anyway. I don't remember any of my Irises having those before.

It's not always easy to get an iris to set seed pods, that's why you have not seen any before. You got lucky.
Renee

I also have many bee pods for the first time this year. I usually deadhead so don't get any, but was slow this year. So now I have a few that I left. I plan to try to grow some on to see what I get. Since there are several varieties with bee pods,I should get an interesting mix. Hope they grow...I think this will be fun.

Does anyone know how long from seed to flower for SDB's?