The Poison Mushrooms is a trap introduced in the 13.0.0 update.
It appears to be a large mushroom or a small mushroom tree with 5 red mushroom and white polka-dotted blocks, 2 blocks of beige mushroom wood and underneath it is some grass.
They spray around poisonous spores that poison all enemies nearby.
- Look at the floor and get away from the trap.
- Shoot the trap and it won't hurt you anymore.