Suitable
What are collar stays?
Collar stays are removable strips of plastic or metal that slide into the pockets at the points of a shirt collar. They stiffen both ends of the collar so it lies neatly and flat instead of curling up. The size differs per clothing brand and per type of shirt, so keep them when you wash: a collar without stays goes limp.
History of collar stays in (men's) fashion
In the days of whaling, from the 17th to the 20th century, pieces of baleen from a whale's mouth were used for this. Baleen is a sieve-like structure in the whale's mouth with which the animal filters plankton from the water. Whale baleen consists of keratin, the same material your nails and hair are made of, and that is exactly what made it suitable: sturdy yet springy. Not only the collars of shirts but also suits, corsets and shoulder straps were reinforced with it. Today the stays are made of plastic or metal.