Complex sentence: Size may vary, depending on the size of stone it grew up upon, ranging wildly from 2 cm to 30 cm. There have been reports of unusually large stone crayfish in deep sea conditions.
Split into simpler sentences: Size may vary, depending on the size of stone it grew up upon, ranging wildly from 2cm to 30cm. There has been reports of unusually large stone crayfish in deep sea conditions.