Misc: What method of communication was invented in 1837?

Questions

Any of as many as 50,000 marine, freshwater, & terrestrial species of mollusk?

Any of the drugs used to reduce nervous tension or induce sleep?

Any of various scientific recording devices designed to register a persons bodily responses to being questioned?

Any of various viruses that are parasites of bacteria?

Any structure of animals, plants, or insects that produces chemical secretions or excretions?