Galastropods

Galastropods, also known as Space Snails, are fauna that may be found in Astroneer. Following a chain of missions using the Xenobiology Lab, the player will unlock all seven snail friends, one for each planet. Each snail provides a different buff, that requires feeding various hazardous flora seeds to activate. Feeding the snail their favorite seed activates the buff for 30 minutes, or 10 minutes if fed any other seed. The ring on top of the terrarium will be blue while the buff is active, and red while active but in the wrong slot on Princess, Bestefar, and Enoki's terrariums, as they require being in either the backpack or on the Terrain Tool.

Source
During a playthrough, players will gain access to a mission that requires mining 3 Sphalerite. Completing the mission will reward players with a Strange Object that, when picked up, displays a hologram of the Xenobiology Lab. Placing this hologram on the ground and activating it will spawn in the lab through a rift.

Acquiring a snail will require scanning 5 discarded shells on the same planet as the snail. Afterward, players will be rewarded with a terrarium used to house the snail. Players will then be tasked with filling the terrarium with a soil canister, a seed, and a resource, in order to make a proper environment for the snail.

Once the terrarium has been completed, collecting a snail requires turning the terrarium into a musical bait. Placing a Small Trumpet Horn or Small Squeaker Horn on the terrarium will activate the bait, causing music to play from the horn and the galastropod to appear nearby. Players must then approach the snail and activate a dance emote to please the snail before it digs into the ground and relocates. After this process has been repeated enough times, players can then befriend the snail, causing it to enter the terrarium.

Galastropod Shells
Galastropod Shells can be found on every planet, with each planet having a unique shell type. They may be scanned to obtain Bytes, either directly or in a Research Chamber, or placed in a Shredder to obtain Scrap.

Trivia

 * Galastropod is a portmanteau of galactic and gastropod.
 * Each Galastropod has a species, based on the planet they are found on, each in the genus of Galastropoda. This is based on real world snails being part of the Gastropoda genus.