Found this hard, foam-like brown structure attached to a fence post in the backyard. I was about to scrape it off but hesitated. What is it?

These Egg Cases Around the Yard
Praying mantis egg cases can be found in a variety of locations around your yard, typically in spots that offer some degree of protection and camouflage. You may discover them attached to the branches of shrubs, within dense vegetation, or on sturdy surfaces like fence posts and garden furniture.
The strategic placement of the ootheca helps to ensure that the emerging mantises have immediate access to food sources such as small insects. By placing the egg case in sheltered, yet open environments, the female