Cobalt

Here in Nottingham we put ham in a cob for lunch. We have a chip cob after a night out. And there is no way we are calling that a roll, barm cake, or bap.

According to Wikipedia, the word could have originated as a variant of cop, meaning head. Cob could also have come from the English word cot for cottage, the Welsh cob for top of tuft or the German Kuebel, a large container.

The word cob was also mentioned in clergyman Mackenzie Edward Charles Walcott's book, Traditions and Customs of Cathedrals, published in 1877.

It read: "The cob was a cracknel or simnel made of fine flour."

Cobalt was discovered by Swedish chemist George Brandt in 1735. He isolated the element and proved that it was the source of the color in blue glass which previously was thought to be from bismuth. 

Cobalt compounds were used throughout ancient history by civilisations such as Ancient China and Rome to make blue glass and ceramics. 

Cobalt is also important for animal life. The body uses it to create certain enzymes. It is also a component of the vitamin B₁₂.