Obeth Arnesian is an unseen character mentioned in Sinderion's Field Journal.
According to the journal, Obeth was a treasure-hunter who had been exploring Blackreach, when he came upon what he had assumed was just a "noisy red weed." Being unsuccessful in finding anything else of value, he took the weed, hoping to find someone who would find it of value. After much searching, he tracked down Sinderion, a Nirnroot enthusiast in Skingrad, Cyrodiil. Sinderion paid Obeth 1,000 septims, and they never crossed paths again.