  Magic angle twisted trilayer graphene (TTG) has recently emerged as a new
platform to engineer strongly correlated flat bands. Here, we reveal the
structural and electronic properties of TTG using low temperature scanning
tunneling microscopy at twist angles for which superconductivity has been
observed. Real trilayer samples deviate from their idealized structure due to a
strong reconstruction of the moir\'e lattice, which locks layers into
near-magic angle, mirror symmetric domains comparable in size to the
superconducting coherence length. The price for this magic relaxation is the
introduction of an array of localized twist angle faults, termed twistons.
These novel, gate-tunable moir\'e defects offer a natural explanation for the
superconducting dome observed in transport and provide an avenue to probe
superconducting pairing mechanisms through disorder tuning.
