If an instrument has a range too high or too low for composers to easily write its music on bass or treble clef, the music may be written either an octave higher or an octave lower than it sounds, in order to reduce the use of ledger lines. —Wikipedia
So I'm playing piano, and there's suddenly a passage where I need to play the notes written on the bass staff, but an octave lower. The notation for this is the bass clef, possibly ornamented with a written notation to play an octave lower.
Or I'm playing some instrument that normally plays in two octaves, one corresponding to the treble clef and the other an octave higher than the treble clef, and — both are written on treble clefs, one above the other??
This seems terribly confusing. Why not use another clef symbol, one that unambiguously indicates the correct octave? (I'm assuming such a symbol exists; if not, why not?)