A verble that functions as a adjectuve and can be past or present

A participle is a verbal that functions as an adjective. Two kinds of participles: A. Present participles, always ending in -ing, are created from the form of a verb used with the verb to be ( am, is, are, was, were, been) as an auxiliary verb (progressive tense).

Explanation:

moon-letters were a method of writing invented by the dwarves. moon-letters were ordinary runes, but written in such a way that they could only be read when the light of the moon shone behind the writing. some moon-letters could be read by any moonlight, but it was possible to make the writing even more secret. more sophisticated moon-letters could only be read by the light of the same shape of moon, or at the same time of year, as when they were written. hope this !

the words “strangest” and “unusual” suggest that the narrator is about to tell the story of an odd or puzzling group of people.