Hi donnag61,
I don't come to the cactigallery much, just stopped by to post a picture and I see no one has answered your question.

It's is the fruit/seedpod. I don't know a lot about them so I can't tell you anything else, but I've included the link to the google page I ( where I checked to make sure it was a seed pod) and seems to be quite a few places where you and I can both learn more.

Here is a link that might be useful: google

It's a seed pod