A hornito is a small, conical volcanic structure formed by the extrusion of lava through cracks in a solidified lava flow, often resembling a small spatter cone. Hornitos are important in understanding volcanic activity, the dynamics of lava flows, and the features associated with effusive eruptions.
Reference: Parfitt, E. A., & Wilson, L. (2008). Fundamentals of Physical Volcanology. Blackwell Publishing.