* Flat top: The summit of many volcanoes can be flat due to erosion or the formation of a caldera (a large crater).

* Extremely steep sides: Volcanic cones are often characterized by steep slopes due to the accumulation of lava flows and ash.

* Round or oblong shape: Volcanoes can take on various shapes, but many are roughly circular or oval in plan view.

Let me know if you had something else in mind!