Peace Lily Green Blooms: Aging or Wrong Plant?

Your peace lily blooms were white, now all green. Two possibilities:

1. Normal Aging

White spathes naturally turn green as they age. Clip at base to encourage new blooms. Fertilize with bloom booster.

2. Two Plants in One Pot

If blooms never were white (green from start), you have a Chinese Evergreen (Aglaonema) mixed in. Their blooms are green and look similar. Fertilize both. They can share a pot.

Check Google images for Chinese Evergreen to compare.