This fossil lobster, 100 million years old, possesses the same physical structure as lobsters today. Some lobsters display migratory behaviors that are very interesting. In the course of such migrations, lobsters line up so that each one can touch the one in front of it. In this way, a convoy of between 50 and 60 lobsters is formed and moves along the ocean floor day and night for several days. Migrating in a line enhances the lobsters" ability to move. The resistance encountered by a lobster advancing through the sea water individually is halved when another lobster is moving in front of it. (The same principle is exploited by modern-day trucks and race cars.) Because of this linear movement, lobsters can cover more distance in less time, while expending less energy. Some species have been observed to travel as much as one kilometer in an hour.