I was in a server, using the true alpha texture pack and i saw a broked house. i went inside and i saw a trapdoor. i right clicked it and it opend and 1 second later it instantly closed. i tried to break the trap door and it vanished. i walked away from the house and for a second i saw the green wither.

for those who dont know what the green wither is the green wither is a faceless wither with green and white parts on his body

the version it happend was 1.18