Though it released almost 10 years ago,Terrariastill draws in thousands of players due to its accessibility and deep gameplay. The developers are still working on it, releasing an update called “Journey’s End” as recently as last October.

There are several ways to progress throughTerraria’s 2D sandbox, but the main way to advance through the game is by defeating the bosses. Each boss unlocks a new stage or new area with powerful loot, and some, like the Brain of Cthulu, drop resources that will give players their first truly powerful set of tools and armor.

crimson hearts in terraria

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Here’s how to get Tissue Samples, the primary drop from the Brain of Cthulu, and what they’re used for.

How to Get Tissue Samples

The first step to getting Tissue Samples comes before the world is even generated. It’s important that in the menu, when selecting the parameters for the world, a player choosesCrimson instead of Corruption.The Brain of Cthulu is only available as a boss in worlds that contain Crimson.

The Brain of Cthulu is one of three bosses that are available to fight to start the game. To ensure the fight is relatively easy, players should have at least Platinum armor and some Platinum gear, though the type of weapons and accessories use vary depending on what type of class-build a player is using.

To spawn the Brain of Cthulu, head deep into the Underground Crimson and search for floating objects called Crimson Hearts, which look like glowing anatomically correct hearts. Below is a picture of Crimson Hearts for reference:

Crimson Hearts can be broken with either a Hammer of any power or Explosives. Each one drops aunique and rare itemthat cannot be obtained otherwise, including a Gun, which is useful to unlock more powerful Firearms down the line. Breaking three Crimson Hearts will spawn the Brain of Cthulu.

It can be a challenging boss if players are unprepared, as it undergoes multiple stages the more damage it takes. It emits floating eyeballs called Creepers which, upon death, will drop Tissue Samples. Players will get more Tissue Samples on higher difficulties.

On every difficulty but classic, the Brain of Cthulu will drop a Treasure Bag once it has been defeated. It contains several useful items, including 10-19 Tissue Samples on both Expert and Master. A player needs to collect 106 Tissue Samples to craft each related item.

What Tissue Samples are Used For

Tissue Samples are necessary to craft the best set of armor and tools Pre-Hardmode. Each piece of Crimson Armor or Crimson Tools also requires Crimtane Bars, which can be collected from the Eye of Cthulu or the Brain of Cthulu. Here’s how to craft each piece of armor and each tool.

Players can also use Tissue Samples to craft theVoid Bag and the Void Vault, which are two useful items that can expand the inventory, though both are only craftable after defeating Skeletron, the most difficult of the first three bosses.

Terrariais out now on 3DS, iOS, PC, PS3, PS4, PS Vita, Switch, Xbox 360, and Xbox One.