Evidently Peul hairstyle I am thinking. Sorry no source for photo. The Photographer is perhaps accredited somewhere in the many pics on Pinterest (my pet peeve with Pinterest is that so many photos are poorly or mistakenly described or unaccredited). This does not show the grouping of the shells- though maybe a looser gather, but does show them being worn:
Bead lover, collector since Age 15, semi-retired had wholesale/retail bead, folk art, tribal art store Lost and Found Gallery for 25 yrs. in DT Greensboro, NC