Answer:
It's a verb
Explanation:
Verbs are action words, "riding" is an action
Cob has been used since the 17th century as a building material. It is made by mixing dry sand, sifted clay and water. A cob house is a house that is made from this material. A benefit of using this material, is that it is sustainable and only uses natural products.
This happens quite a lot in verbs e.g run to running. It is because you double the last consonant in a one-syllable noun for it to become a verb. (Keep in mind there are exceptions to this rule.)
I think that It's being used as a reflexive pronoun. "Jolly band of pirates" and "we."
Hope this helps! (:
