As the Kilauea volcano continues to spew lava onto the Big Island of Hawaii, more instances of unique aspects of volcanic activity emerge such as the recently seen “lava balls.”

These balls of lava, also known as lava boats or lava bergs, can be seen in a new video that the United States Geological Survey (USGS) tweeted on Saturday. The time-lapse video shows lava flowing from Fissure 8 and on the stream of lava are accumulated cooled chunks that float on top, hence the term lava boats or lava balls. Sometimes these orbs will break off from larger portions cooled-off molten rock and other times they’ll form when lava cools on the surface as it flows. The problem with lava balls is that they can accumulate to divert the flow of lava.

Read more at Inverse.