This is either a bit of fibrous plant material or a piece of a fairy cloak (it looks like woven cloth). Burmese amber, 99+ million years old. The inclusion measures a whopping 2 mm in length, while the whole piece of amber is 17 mm long. Pics 1 - 3 are top views, pic 4 is from the underside (harder to get) & pic 5 is the entire piece with the inclusion circled in red. The inclusion is also curved (of course) making it difficult to photograph.

Not really sure if they had a written language back then & if they did, would anyone be able to read it?