I found a white soft cottony or spongy lumpy ball the size of a small marble on the underside of a spearmint leaf that had a little hole in the side where the occupant had already exited. I live in zone 6. What could it be?

Hi, Delores. to ATP.

It's most likely a Spittlebug.
http://boomerempowerment.com/h...

I've never treated any of my plants to control them. Mints in particular are generally tenacious enough to survive them quite easily.

I agree. I don't treat for them either. I currently have some in my basil.

Thanks for your input but I thought a spittle bug had a foamy case this is solid but soft.

Does it look like this?
http://www.ipm.ucdavis.edu/PMG...

no it doesn't. It is totally round and it was on the leaf not a stem and only one and the hole " it" came out of was perhaps 1/16 in diameter

Possibly a spider egg case.

https://www.google.com/search?...

Jay beat me to it; that was going to be my suggestion.

Would you have any idea what kind of spider? I've never seen anything like this before but I do have many kinds of spiders here.

Without a photo, I couldn't even begin to guess. You might want to scroll through the picture on the link I gave you, and see if any match what you have. Then visit that page to see if it gives an ID.

Thanks for the site. I found 2 that were similar to what I have. One in California that couldn't be identified and one in Utah that didn't have a species given then I seen one sort of like what I have and it was listed as a crab spider but the one in California comes closest to the picture so I think it is a spider of some kind. Thanks so much everyone for your help.. Dee