operculum

"The science class learned that the fuzzy mold on the bread had tiny sporangium at the tips of its stalks, each filled with hundreds of spores ready to spread. "

"The student was partially prepared for the exam, but still felt nervous. "

"The aquifer's underwater supply of fresh water is crucial for the town's water system. "

"He released his grasp on the lever."

"The birds had built an amazing structure out of sticks and various discarded items."

"He listened carefully to his mother's concerns, feeling sorrowful about her disappointment. "

"He covered the baby with a blanket."

"to detach the tag from a newly purchased garment"

"The dispersal of seeds by the wind helps new plants grow in different areas. "

"A cat is an animal, not a plant. Humans are also animals, under the scientific definition, as we are not plants."

"Before the big presentation, Sarah took a deep breath and felt more calm. "

"to allow a servant his liberty;  to allow a free passage;  to allow one day for rest"