Hive minds are a type of mob that spawns in the world. They will spawn with a shell of hardened resin around them at the start. Hive minds will spawn mynocks on conveyor belts within several hundred blocks of them (mynocks will not spawn above -100 on easy mob settings). Whenever a mynock eats something off of a conveyor belt, it will "send" that item back to the hive mind which will then grow a new block of hardened resin. The growth pattern is essentially random but will tend towards making tentacle-like shapes.
Hardened resin cannot be easily destroyed. It must be destroyed by bombs, nano-disintegrators, or the machines involved in mining and processing resin.
It is recommended to avoid allowing any hive minds to grow unless you are explicitly attempting to mine resin from them. If something you care about is covered by hardened resin before you are capable of destroying it, it can be a major setback.
All of your conveyor belts (that a mynock could spawn on) should be defended by turrets to avoid feeding hive minds. The more the better as a mynock could still eat a few things before it is killed if the turret cover is inadequate.
Hive minds can be easily killed after exposing their core and do not pose any risk to the player.
Hive minds can be seen in the holobase as either a green cube or a purple spider-like structure. Mynocks can be seen by a red sphere around your conveyor belts.