A common drilling problem is that something breaks in or falls down the well during drilling. The fragment from the break of the tools above are called fish or junk. The process to take the fragment away from the well is called fishing and it use a tools called fishing tool.
Hyne, Norman J. 2012. Petroleum Geology, Exploration, Drilling & Production. Oklahoma. PennWell Corporation.“Fundamentals of Onshore Drilling Fundamentals of Drilling” Presentation from IGI.