That really looks like a seed to me too . . . have you tried brushing it with a damp Q-tip? If it is, it'll probably pop right off when brushed from below.
(not-so-funny but related story: My conure had a small "hang-nail" on the side of her beak -- since fixed by the vet -- and one night it appeared like a crack had formed from it up through the top of her beak. Panic set in as Dr. Google gave it's prognosis, and we took some more pictures . . . and realized the crack was a sliver of a canary seed husk
Quick brush with a Q-tip and she was back from "life-threatening injury" to "Poor baby, that looks uncomfortable". Try to brush it off -- your nerves may thank you.)