Greetings, could this possibly be a snail?  The photo is too blurry to zoom in on it.  Snails can be a problem in nurseries just like slugs are a problem in a garden.  You should remove it if it is a snail and destroy it.  Otherwise, please take a clear image that is closer and send it back to us.  

PS- are you sure this is Mimosa?  

Hi. It's not a snail. It's a small, hard pod, oval in shape. As I explained previously, when I scraped it off I found it was filled with eggs. I am attaching a photo of what it looks like now, a few days post-scraping.

And yes, the tree is a mimosa.

Sehvilla, after a bit of thought, I'm wondering if this is a scale insect. It wouldn't be altogether unusual to find one in a nursery setting. I'll wait until I hear from other colleagues to follow up. In the meantime, try comparing it to something like the European fruit lecanium (Parthenolecanium corni) on this UC IPM page (third photo down). Would you say it looks similar?

Best regards,

Jeremy

I should note that I used Parthenolecanium corni as a comparable example. It's a well-distributed pest, but I'm not at all certain if that's the correct species. If you're interested in taking it down to species, we would have to submit the sample to our diagnostics lab.

Mimosas are lovely trees. One think you might consider is to keep an eye on it to make sure there aren't a bunch of young scales growing on it. If you do find some, we can talk about management options.

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