Ender Chests are blocks that can store items. Ender Chests function the same as normal chests, except that their contents are shared across all other Ender Chests placed anywhere, even in different dimensions.
Ender Chests do not drop their contents when broken. Items placed inside will remain persistent even if all Ender Chests are destroyed, and can be accessed from new Ender Chests. Ender Chests have half the blast resistance as Obsidian, making them still immune to explosions. They also emit light and a particle effect similar to that of an Enderman and Nether Portal. In SMP, Ender Chests have a separate inventory for each player. Destroying one will only drop 8 obsidian (unless broken using a pickaxe enchanted with Silk Touch), meaning another Eye of Ender would be required to craft it again.
Ender Chests cannot be made into double chests and thus can be placed adjacent to each other normally.
Eye of Ender