For determining ability scores, the closest creatures I can find are...
Mosslord (L, 20 HD): Str 33, Dex 12, Con 28, Int 15, Wis 18, Cha 19
Shambling Mound (L, 8 HD): Str 21, Dex 10, Con 17, Int 7, Wis 10, Cha 9
Obliviax Mossling (D, 1 HD): Str 5, Dex 15, Con 14, Int 8, Wis 13, Cha 14