YOU SAID:
Alex was put in a glass coffin
INTO JAPANESE
アレックスはガラスの棺に入れられた
BACK INTO ENGLISH
Alex was placed in a glass coffin.
INTO JAPANESE
アレックスはガラスの棺に入れられました。
BACK INTO ENGLISH
Alex was placed in a glass coffin.
That didn't even make that much sense in English.