I pulled out 6A Features of Sophocles plays: ODES because I hadn’t realized until I got the blue Congratulations! box that I’d done today’s puzzle from 2010. But it proves that for more than a decade ODES has been a go-to answer in the New York Times Crossword Puzzle.

Theme:

17A In consecutive order: SEQUENTIAL -> (S)(E)QUENTI(A)(L) -> SEAL.
25A Just barely legit: BORDERLINE -> (B)(O)RDERLI(N)(E) -> BONE.
36A What a slow person may need: HEADSTART -> (H)(E)ADSTA(R)(T) -> HEART.
50A Slip-up: MINORERROR -> (M)(I)NORE(R)(R)(O)(R) -> MIRROR.

59A Fragile articles … or a hint to the things named by the circled letters: BREAKABLES.

Break a seal, break a bone, break a heart, break a mirror.

Finished this one in 7:29.