One for an object head challenge, the Periodic Table of Elements.
Argon, the Noble Gas; and Mr. (Sr) Strontium.
(Sr, strontium symbol is the abbreviation of mister in Spanish. El Señor Estroncio -please don’t read that on Alan Davies’ Spanish voice-. I used that as a mnemonic thing to remember the symbol and the name. Strontium is the only element symbol I can remember. Well, and the easy ones, oxygen, hydrogen, sodium)