Picture shows a Sekizoku without a projection (Mukei Sekizoku), although there are Sekizoku that have a projection opposite the pointed top of an arrowhead and these are called Yukei Sekizoku (Sekizoku with projection).
写真は突起をともなわない石鏃（無茎石鏃）であるが、矢の先端の反対側に突起（茎）をもつものもあり、これは有茎石鏃と呼ばれる。