Well established reef system. Got a shipment of dwarf Cerith snails in and I think I got these hitch hikers along with them. I know they are flatworms and normally white ones I had in the past did no harm but, they were bigger. These are tiny , 2-3 mm long and under blues and white light, they have a brownish body with a blue head. Just white light… they look white. Need I be concerned? While a 6 line take care of them? Thanks!