English: Basaltic lapillus from Ascension Island in the Atlantic Ocean. (~59 millimeters across at its widest)

Volcanic eruptions produce a variety of igneous products that vary in size, shape, and composition. Terms based on clast size include volcanic dust (less than 1/8 of a millimeter), volcanic ash (1/8 to 2 millimeters), lapilli (2 to 64 millimeters), blocks (angular tephra larger than 64 millimeters in size), and bombs (non-angular tephra larger than 64 millimeters in size).

Seen here is a large lapillus from a volcanic deposit on Ascension Island in the Atlantic Ocean. The island is a hotspot - a site of volcanic activity atop a large mantle plume. Other examples of hotspots include Iceland, Afar, Yellowstone, and Hawaii.

Like volcanic bombs, lapilli vary in shape. This one is a fusiform lapillus. It is composed of vesiculated basalt.

Age: likely Holocene

Locality: unrecorded site on Ascension Island (Ascension Hotspot), west of the Mid-Atlantic Ridge, equatorial South Atlantic Ocean.