+2 DEX or CON +1 any other score

Being a fungus, they cannot see the same way other creatures do, they can however sense objects nearby and feel movement up to 20ft away through vibrations.

within the radius of their tremor sense they have advantage on perception checks to hear and disadvantage outside the radius

They are vulnerable to cold and fire but resistant to slashing and piercing. Also immune to psychic.

Being what they are, they require a host to survive for long periods of time

They are unable to swim well, in cold water not at all, but they don't need to breath for up to 15 minutes.