A spherical stromatolite that usually forms around a fragment of detritus such as a piece of shell or a grain of sand.
A stromatolite that is spherical rather than dome-shaped. Oncolites usually form around a nucleus consisting of a detrital fragment (such as a shell fragment or a grain of sand) and are less than 10 cm (3.9 inches) in diameter.
Origin of oncolite
- Greek onkos mass oncology –lite
From American Heritage Dictionary of the English Language, 5th Edition