Minecraft has introduced several new mobs in recent updates, each with their own unique abilities and mechanics. Here is a summary of the new mobs and what they do:

1. Sniffer: This mob won a public vote to be included in the game and has the ability to detect hidden objects in the desert biome.

2. Rascal: This mob was one of three options in a mob vote and has the ability to give players more time in mines.

3. Tuff Golem: This mob was also one of three options in a mob vote and has the ability to help simplify storage systems while decorating a base.

4. Warden: This boss mob was teased for the Minecraft 1.18 Caves & Cliffs update and can only be found underground in the deep dark caves biome. It is the first blind mob in the game and relies on sound and vibrations to hunt players.

5. Allay: This cute creature was the result of a user choice mob vote and picks up dropped items and collects copies of that item from the loaded chunks of your world.

6. Crab: This mob is one of three options in a current mob vote and has one gigantic claw that it likes to wave around as it scuttles through its home in the mangrove swamp. This claw is special because if it hits a player, it will deal damage and knock them back.

It is worth noting that some of these mobs are not yet available in the game and are still in the testing phase. Players can vote for the Crab mob to be added to the game in the upcoming Minecraft 1.21 update.