The mechanical dog (sometimes also called a plasma dog or a robot dog) is a specialized persistent mob that you can keep as a pet. Unlike real dogs, mechanical dogs are immortal. They never despawn and cannot be destroyed. So if you're feeling lonely in your newly-built house, bring home a mechanical dog, and you'll never be lonely again!
How to Obtain
Mechanical dogs come from dog crates.
How to Use
Place the crate in a confined area, then click on it. Your dog will appear, complete with its own pre-assigned name. Mechanical dogs can jump up two blocks and can cross diagonal blocks, so make sure to build your enclosure carefully. It's best to make sure you don't use any material that can be shoveled.
Pets in Deepworld require no upkeep or maintenance, so one you release it from its crate, you're all set.
Released December 2013 as part of the 1.14.0 update.
Pets used to factor into the mob mechanics of spawning, which meant you could suppress all spawning on a world by simply opening lots of pet crates.
For a short time, it was possible to destroy pets with explosives. They would reappear next time you logged in, though.