| Clue | Source | Date |
|---|---|---|
| Fingernail makeup | Wall Street Journal | 09 Jan 2021 |
| Fingernail material | Universal | 08 Aug 2020 |
| Protein from European rodent in family | The Sun Two Speed | 09 Jul 2020 |
| Hair constituent | The Sun Two Speed | 09 Jul 2020 |
| Protein in horns and hair | Canadiana | 22 Jul 2019 |
| Protein found in hair and hooves | New York Times | 07 Jul 2019 |
| Protein in hair straighteners | USA Today | 09 Jun 2017 |
| Protein found in hair and nails | The Telegraph Quick | 14 Mar 2017 |
| Jack ultimately has age and can nail constituent | The Telegraph Cryptic | 14 Dec 2016 |
| Makeup of some nails | Wall Street Journal | 22 Sep 2016 |
| Horn material | ||
| Fingernails, essentially | ||
| Hair protein | ||
| Protein in hair and nails | ||
| Nail material | ||
| A fibrous protein | ||
| Fibrous protein | ||
| Nail or horn base | ||
| Fingernail component. | ||
| Basis of horny tissue. | ||
| Tissues of fingernails. |