The elegant twisted beard on this example is unusual and may be an innovation by the artist, Musa Rabkabaw, who created it.
General information about ‘Bena Healing Vessels:
Living to the immediate west of the Ga’anda are the ‘Bəna peoples who share certain cultural practices with their neighbors. You will notice that these vessels bear a strong resemblance to Ga’anda Mbir’thleng’nda in their radically cantilevered heads and spiky texture. The ‘Bəna use them for curing skin ailments, the symptoms of which are revealed in the character of a vessel’s “skin.” Their style and usage reinforce the shared reservoir of ideas among peoples in the Upper Benue Valley.
Source: Gallery Wall Text, Central Nigeria Unmasked: Arts of the Benue River Valley, 2011