The Minecraft 1.21 update is known as the "Forests and Fossils Update". However, this information is not accurate as it is a fan-made update. The official Minecraft 1.21 update has not been released yet, but there are speculations and suggestions from the community about what it might include. Some of the expected features include:

• Archaeology: The update is expected to introduce an archaeology system where players can dig up shards of clay to turn them into pottery.

• New biomes: The update is expected to introduce one or two new forest biomes or one new forest biome plus improvements to existing forest biomes.

• New mobs: The update is expected to introduce new mobs such as the Grizzly Bear, which loves honey, and the Breeze, a new hostile mob that uses wind as a weapon.

• New structures: The update is expected to introduce a new structure called Trial Chambers, which is a different type of challenge for combat-loving players who have been wanting a different spin on the action within Minecraft.

• New blocks and items: The update is expected to introduce new blocks, items, and biomes.

It is important to note that these are just speculations and suggestions from the community, and the official features of the Minecraft 1.21 update have not been confirmed yet.