Marsh plants react to the sound of this bell, bending to open the way without you having to touch them.
The Green Tinkler is a mysterious bell whose tones resonate with the plants of the Hydra Marshes. Specifically, the ring of the bell causes some plants to bend down or away from the instrument's user, allowing access over steep embankments. Serge received one from a Dwarf in Guldove (Another) after Kid became poisoined.
From: Key Items (Chrono Cross)