Life In 19x19

I'm having difficulty placing the Tortoise Shell between A tier or S tier. I'm inclined for it to be A-tier.

$$ Tortoise Shell
$$ .....
$$ ..X..
$$ .XWX.
$$ .XWX.
$$ ..X..
$$ .....

The Tortoise Shell occurs when 2-stones are captured. Black has spent 6-stones for the arrangement, while white has ...

Consider
$$c The Smallest Formal Eye?
$$------
$$|.X..
$$|X.X.
$$|XXX.
$$|....

This is a two-headed dragon that is already pass-alive

Perhaps I focused too much on the single-eye shape. The double-eye shapes are certainly more efficient: "corner 6 life", "side 8 life", and "center 10 life ...

$$ Bamboo Joint
$$...d...
$$..XaX..
$$..XbX..
$$...c...

I rate the Bamboo-Joint F-tier for eyes. While this is one of the strongest connection shapes in the game, its pretty awful at making eye-space. The a and b points are miai, the connection cannot be severed in typical circumstances because ...

Over on Reddit's /r/baduk, I made a post about Eye Shapes. People didn't like the ASCII diagrams though, so they wanted me to remake the diagrams here.

The original topic: https://www.reddit.com/r/baduk/comments/rvctn5/eye_shape_tier_list/

I'm roughly a 10k player. So I know I'm not the best, but ...