Given a scientific passage and an answer, generate a question for the given answer.

Passage: Platelets are cell fragments involved in blood clotting. They stick to tears in blood vessels and to each other, forming a plug at the site of injury. They also release chemicals that are needed for clotting to occur. Answer: platelets
What is the term for the cell fragments involved in blood clotting, which stick to tears in blood vessels and to each other?