"French crabs" and conchoidal fractures

The "French crab" tree being now 20 years old, finally decided to come out in her first fruiting. A rather enormous crop, too.

A Pippin of a Question
I always wanted French crabs, and put the question to all who know: What are these? For surely, if they are French crabs, I'm Dame Lobster Ther M'Dore, which reminds me to post this scrap here: "[A]n oyster long out of his shell (as is apt to be the case with the rural bivalve) gets homesick and loses his sprightliness"

The so-called "French crabs" posing with a Smyrna quince

Technical description: Many of these apples have stems that look like outie belly buttons

I'm not complaining, mind you. These are apples as apples should be, cracking with a sound like the earth breaking in half. These apples are so hard that one could be tempted to look for a Mohs Hardness rating, but that would be wrong. Mohs Hardness (not named after Mr Moh but Mr Mohs, who was born to be difficult) rates the resistance to scratching, and everyone who knows anything fun about MH knows that diamonds, which cream the competition when it comes to MH, can be smashed with a hammer. These apples would just laugh. You need your teeth for these gems, or a chisel.

The taste is so rich that the mouth is overwhelmed with appreciation.

Conchoidal fractures

"There were jellies, which had been shaking, all the time the young folks were dancing in the next room, as if they were balancing to partners. There were built-up fabrics, called Charlottes, caky externally, pulpy within; there were also marangs, and likewise custards,—some of the indolent-fluid sort, others firm, in which every stroke of the teaspoon left a smooth, conchoidal surface like the fracture of chalcedony …"
— Elsie Venner by Oliver Wendell Holmes (this is also the source of the oyster truism)