"Machine" is a word that loosely refers to any blocks that can be used to perform an action, like a crafting table or a furnace. Fossils and Archeology Revival adds several machines that are vital to the creature-reviving and relic-restoring processes of the mod.
There are quite a few blocks that the player can come across during their archeological adventures. Some are crafted and repaired by the player, but others are rare and only occur in structures or other dimensions.
With so many mobs that need enclosures and different structures that can be found, the mod requires a few extra building blocks than what are provided in vanilla Minecraft. Most of these blocks are crafted out of blocks mentioned above and are purely for decoration; however, dense sand and reinforced glass were added in order to contain dinosaurs that can break blocks without forcing the player to use unsightly iron blocks.