“My sister-in-law, who lives one floor up, called me and asked if my doorbell had been ringing too,” said Lisa. You keep hearing the doorbell ringing, but you don’t see anyone. It wasn’t until they had all gathered at the front door and Lisa’s husband looked at the doorbell that the culprit was finally identified. “I said, ‘I know who rang the bell!’ There was a slug sitting right on our nameplate. These mollusks, often described as shellless snails, are most active at night, since they prefer cool and damp weather.