A Hammer is a tool used by Fossil Fighters within the Fossil Fighters franchise since the first game.
Hammers are used to remove large amounts of excess sediment from fossils. However, Hammers can also break fossils just as easily.
You can buy a Hyper Hammer later, which is noticeably stronger than the Hammer. The Hyper Hammer costs 25,000 Gs. An integral part of cleaning, the Hammer smashes layers of the rock, but has a bigger risk of damaging the fossil inside. The Hammer is also the only tool that can penetrate the outermost layer of a Dark Fossil Rock. In one of the cleaning sidequests, specifically smashing Duna's boulder, the Hammer is particularly for destroying objects. An important thing to note is that although the Hyper Hammer is stronger, it breaks fossils very easily, so one must be careful when using it.
In Fossil Fighters: Frontier, there are different types of hammers, with these hammers connecting to your Bone Buggy. In the beginning, you start with the weakest Hammer, and as the player progresses later in the game, stronger hammers become available to break apart harder rock faster. The stronger the hammer however, the greater the weight the hammer bears onto the player's current Bone Buggy.
There are also EX Hammers, which are lighter versions of the standard Hammers, and thus lessen the burden on Bone Buggies for the player to use other options. Unlike the regular Hammers, the EX Hammers can only be obtained by competing and winning the Seven Scramble's five Ostrom Cups in the Fossil Parks' stadiums, which are only active on Wednesdays.