Avocado leaf spot

I discovered this spot on a fallen leaf from my mature avocado tree this morning. I've had this plant for over ten years and never seen anything like this before. Does anyone know what it is?

 

Looks like where insect eggs were/are.

 

Yup, that's 100% insect eggs. Keep an eye on your tree, but in general they're not anything to worry about - Avocados in the tropics play home to numerous creepy-crawlies without incident.

 

Thanks Daniel . . . I don't see another one on the tree.

Thanks Lorax: it looks like an isolated interloper.