No, Doels also drop Abysmal Eyes and Fangs when you harvest them. The Blood-moon Beast boss spawns Doels around it to bite and distract you. This boss usually appears during encounters/events in certain areas, like up north of the Bridge of Betrayer (F-11 on the map grid) during the "Sacrifice Interrupted" encounter, for example. The Blood-moon Beast was originally designed for the Isle of Siptah map expansion, where it still spawns (during the Maelstrom, at the Fractured Citadel, and the Pools of the Grey Ones (use a Blood-moon Beast figurine in here to summon this boss).