Initially having seen this in a book, I was reminded of it by problem 312 (Weak shoulders)
Surprisingly enough, black often thinks he's unconditionally alive.
(;AB[cc]AB[bd]AB[db]AB[bb]AB[ad]AB[da]AW[dc]AW[ec]AW[eb]AW[cd]AW[ce]AW[be]AW[ea]AW[ae]C[White to kill.]
(;W[ab];B[bc]
(;W[ba];B[cb]C[Indeed - this black shape is dead. If there are big kos on the board, black can use the approach moves (A17/C19) as ko threats.RIGHT])
(;W[ca];B[cb];W[ba];B[aa];W[ba]C[Indeed - this black shape is dead.If there are big kos on the board, black can use the approach moves (A17/C19) as ko threats.RIGHT]))
(;W[aa];B[ba]
(;W[ac];B[bc])
(;W[ab];B[ac]))
(;W[ca];B[cb]
(;W[ac];B[bc]
(;W[ab];B[aa])
(;W[aa];B[ba])
(;W[ba];B[aa]))
(;W[ab];B[bc];W[ba];B[aa];W[ba]C[Indeed - this black shape is dead.If there are big kos on the board, black can use the approach moves (A17/C19) as ko threats.RIGHT]))
(;W[ba];B[cb]
(;W[ab];B[bc]C[Indeed - this black shape is dead.If there are big kos on the board, black can use the approach moves (A17/C19) as ko threats.RIGHT])
(;W[ac];B[bc];W[ab];B[aa];W[ab]C[Indeed - this black shape is dead.If there are big kos on the board, black can use the approach moves (A17/C19) as ko threats.RIGHT]))
(;W[ac];B[bc]
(;W[ba];B[cb];W[ab];B[aa];W[ab]C[Indeed - this black shape is dead.If there are big kos on the board, black can use the approach moves (A17/C19) as ko threats.RIGHT])
(;W[ca];B[cb]
(;W[ba];B[aa])
(;W[ab];B[aa])
(;W[aa];B[ba]))))