Sponges are tools added by Thermal Expansion. They are able to soak up fluids in a 3x3x3 area when placed. There are three types of Sponges: the Plain Sponge, the Magmatic Sponge and the Creative Sponge, the last of which cannot be obtained legitimately.
The Plain Sponge can soak up most fluids except very hot ones. The Magmatic Sponge is mostly the same, except it can also soak up very hot fluids. The Creative Sponge can soak up any fluid; even multiple types at the same time.
When a dry Sponge is placed in the world, it tries to soak up fluid blocks in a 3x3x3 area around it. The Sponge then becomes soaked. As long as a Sponge is soaked, it cannot soak up any more fluids; it has to be drained first. Soaked Sponges can be drained by devices that can extract fluids from items, like the Fluid Transposer. Once drained out, soaked Sponges become dry and can be used to soak up fluids again.
As long as a Sponge is placed in the world, it tries to keep nearby fluids outside its area of effect from flowing in.
Plain and Magmatic Sponges can only soak up one type of fluid at a time. Plain Sponges cannot soak up very hot fluids: fluids with a temperature of 1000 or higher. This includes Lava and Blazing Pyrotheum. Magmatic Sponges, however, can soak up these fluids.
Creative Sponges can soak up multiple types of fluids at once. They also never become soaked. This means that Creative Sponges can be used indefinitely without having to be drained out. It also means that any fluids soaked up by a Creative Sponge are lost forever.