Prismapump

The  is a place-able block which you can purchase from Anita. A set of 4 blocks costs one Bronze Medal and 2 Jacob's Tickets.

Usage
Upon placing down the, placing down water on any adjacent lateral side or on top of it will cause water source blocks to extend in that direction. The water will extend until it hits a block or it runs off of a block. Water placed below the will not be extended, although all other 5 sides will.

This block makes building farms much simpler, as it eliminates the need to manually place water down a line.

Trivia

 * If players have SkyBlock Addons installed, they have to disable the 'Avoid Placing Enchanted Items' function in order to place the block.