Inside a Ceramic Resonator

Here are how the insides of a 455 kHz Ceramic Resonator look like:






Ceramic Resonators (2 pin devices) are not to be confused with Ceramic Filters (3 pin devices).
455kHz is used as the Intermediate Frequency in AM Radio Receivers.
Some more info on these from around the internet:

• Integrity Technology (App note here lists standard oscillator frequencies.)
• Simple RF Oscillator using this
• Experiments with Ceramic Resonators
• Ceramic Resonator Circuit Symbol (Main Site)
• Receiver with Ceramic Resonator