There's no element that spontaneously combusts in the traditional sense. Spontaneous combustion typically refers to a fire starting without an obvious external ignition source, often due to heat buildup within a material.

Here's why elements don't spontaneously combust:

* Elements are pure substances: They don't have complex chemical structures that can easily generate heat through internal reactions.

* Combustion requires oxygen: Elements need to react with oxygen to burn. While some elements react readily with oxygen (like sodium and potassium), this reaction typically requires an external spark or heat to initiate.

However, there are some phenomena that might be mistaken for spontaneous combustion:

* Phosphorous: White phosphorus is highly reactive with oxygen and ignites in air at room temperature. This is often described as spontaneous combustion, but it's more accurate to say it readily ignites due to its high reactivity.

* Pyrophoric materials: These are materials that ignite spontaneously in air, but they are not elements. They are usually compounds or alloys, and their reactivity comes from their specific chemical structure.

In summary: While no elements spontaneously combust, there are materials that readily ignite in air due to their high reactivity.