Morbs can be killed by
- Duplicants (they do not fight back) or
- Temperature above 57 degree Celsius or below 10 degree Celsius
at which point they drop 3 kg Polluted Oxygen. Morbs can be caught with Animal Traps and be delivered to an Animal Relocator. They can jump over 2 tile high walls and over tile gaps. Morbs do not drown.
Morbs spawn naturally in the Caustic biome.
up to 3 Morb spawn after a while on the corpse. If you build a gravestone the Duplicant corpse is removed and no Morb will spawn.
If an Outhouse is full and not emptied soon enough 3 Morb will spawn from it.