m0useanswered grow question 3 years ago That's a big egg could it also be a pupa or cocoon? I think the magnification is throwing me off for its size relative to the perspective.
May help by identifying the region of the globe your from, could be specific to that area.
I would show this to a local garden centre or farmer I bet they would know.
Bugs they tend to hide eggs on underside of leaves vs on top from my understanding. Broad guess its a flying insect of some sort that will prob eat your plant or something on it/aorund it if its a predator bug.
I'd pluck the leave and toss it in a jar till it hatches then kill it if its a pest.
Good Luck!