Printing agent containers

A printing agent container comprising:

• a receptacle having a top wall, a bottom wall opposing the top wall and a sidewall between the top wall and the bottom wall;
• an internal volume defined by the receptacle and that contains a printing agent, wherein the printing agent is disposed on the bottom wall;
• a vibration transducer on the sidewall, wherein the vibration transducer is to generate a signal representing a vibration detected by the vibration transducer and induced by a carriage when the printing agent container is mechanically coupled to the carriage;
• a memory storing information including a container signature of the printing agent container;
• and
• a communication interface to a controller, wherein the communication interface is to transmit, to the controller, the signal generated by the vibration transducer and the information stored in the memory for correlation of the signal and the information by the controller.