I planted some cape honeysuckle (tecoma capensis) bushes in my backyard, I was looking at them today and noticed this thing on one of the branches. About an inch long, about as big around as my finger. It is hard as a rock, it didn't want to pull off easily, so I left it there. Anyone know what is growing inside?

Looks like you have a praying mantis egg there! There will soon be mantis babies all over your cape honeysuckle.

Possibly a mantis egg sac?

Yes! Perhaps you didn't see my previous post due to cross-posting, which is totally fine, but yes, I believe you have a Praying Mantis egg sac.

Hitchhiked from the nursery. Pretty fascinating, kind of looks like a tiny chest-burster from the Alien movies.

If you saw the mantises hatch you'd think that even more! they pour out like shaken soda pop foam.