Not a Crabapple. The inside of those are white and grittyish like a real apple.

What is it growing on (shrub, vine, tree)? What do its leaves look like?

Wild guess: possibly a gooseberry.

i found the same & was told it was passionfruit or starfruit pods, i forgot which *maybe*

That is a mayapple.

You got the apple part right anyways.

They are edible and delicious.

looks like a not ripe loquat what does the plant look like?

it's a walnut. look it up, that's what they look like before they harden and stuff.

crazy right?

my mom says that it is a crabapple.she used to eat them when she was little

Im pretty sure I agree with Lizz on this one. Far as I can tell it looks like a VERY early walnut...

Its from a Quince bush.

For me it is a "butiá", is the little fruit of some kind of palm trees. I use to have one. And those taste incredible.

I was always told they were pre-dried walnuts. So that's three.

That is not a crab apple. I enjoy crab apples. They are very tart and the inside is just like a regular apple. Eating too many can give you a sour stomach. Crab apples should be highly valued. They are not. But they can taste great!