Most lithic raw material is procured as nodules (nodules have rounded edges but can be in various shapes as opposed to a cobble which is rounded and roughly spherical).
Flint is most often found in this form but there is also tabular flint that is procured from vertical or horizontal seams.
Other lithic raw materials may be procured from eroded out material. Raw material such as slate will come in parallel-sided slabs
tabular flint
obsidian nodule
slate nodule