Lichen?

Lichen?

Observation - Lichen? - UK and Ireland. Description: Small, brown, wart-like growths on a hawthorn twig. Readily rubbed off when dry. Pinhead 3mm dia. Is this a lichen?

Small, brown, wart-like growths on a hawthorn twig. Readily rubbed off when dry. Pinhead 3mm dia. Is this a lichen?