Small problem-solving robots designed as tools, whose capacity to learn and sacrifice themselves led Data to defend them as living beings.
Exocomps were created by Dr. Farallon to carry out repairs in dangerous conditions on the Tyrus VIIA particle fountain project. Each unit can fabricate tools and reconfigure its own circuits, and as they learned they began to refuse orders that would destroy them.
Data concluded that the exocomps were alive and refused to sacrifice them during a crisis, a stand that echoed his own fight for recognition. Decades later, the Lower Decks exocomp Peanut Hamper served briefly in Starfleet, becoming a scheming recurring character.