I found an answer on the gardenweb on Houzz: It's a slime mold, most likely- they run the gamut from the consistency of mousse to
that of a gummy bear left out in the rain for a few days. They're both
gelatinous, and a bit fluffy.

They're harmless and rare. It's OK for you to get rid of them since you are not going to upset the environment or anything.

It looks like spray foam from a can. It's used to stop air leaks. BUT--it deteriorates in the ultraviolet light from the sun. It must be covered with some material to protect it, or it turns orange and disintegrates.

That is not a real fix for whatever the problem is in that wall. That needs to be looked at.

Or slime mold. :) who knew!

Thank you, I recently removed bushes from that area and saw this foamy substance. We've been here almost two years. Perhaps I should knock it off and restart it? It doesn't make the space look that attractive...but it sound like it's safe to remove?

Do you have a leak under your window? Is that water damage?

We haven't had a leak since we moved here two years ago. It was covered with bushes at the time of purchase.

It is insulation and I would not be so sure there is no water getting into somewhwere by the look of that siding.

What is on the other side of that exterior wall inside your house? My guess is the previous owners had a water problem. Your siding seems to be a different color than the siding on the wall next to it. That leads me to believe they might have replaced the siding and didn't carry it down far enough and filled the gap with spray foam. Let us know what the interior wall looks like and we will go from there.

The paint appears to be bubbling, do you not see that? Is this part of the house an addition? For sure cut away the insulation. You need to find out what is going on there. The foam is called Great Stuff if you want to learn more about it.