Here are some ideas for things that could be in the Deep Dark, that could allow the player to replenish their supplies:
Coalified Wood:
Coalified wood is a type of wood that is found in vertical logs buried in the deep dark. It is dark-grey in colour, like coal. It can be used just like other woods, despite being made of coal
Cave Fish:
Cave fish are fish that are present in underground water sources, including in the deep dark. They could be pale-pink, with larger fins, no eyes, and red cheeks. They would serve as a source of food in the deep dark
Sculk-Borer:
Sculk-Borers are a food source exclusive to the deep dark. They generate as small siphon-blocks, attached to deepslate. When the player gets within mining range, or somehow mines them some other way, they retract into the deepslate. If the deepslate is destroyed, the sculkborer will spawn in as a mob, and try to flee. They could appear as a sculk-colour-scheme snail with a siphon on the side of the head, and 2 small wavy things like on a sculk sensor. They would detect vibrations like a sculk sensor. They would drop sculk meat, which can be cooked and eaten, and sculk mantle, which can be used to make bundles or leather, like rabbit hide. If they escape, and leave the player's sight for a while, they would despawn and leave a siphon-block reseting to their original form
Cocoons:
Cocoons are pairs of silk blocks that can be found in the deep dark. Silk blocks are mechanically the same as wool blocks. Cocoons can be brown, grey, or black. When a block in a cocoon is broken, a silk-worm will spawn. Silk-worms are similar to silverfish, but larger and longer. They will attack the player that broke their cocoon, with attack-power and defence similar to a spider
Here are some ideas for things that could be in the Deep Dark, that could allow the player to replenish their supplies:
Coalified Wood:
Coalified wood is a type of wood that is found in vertical logs buried in the deep dark. It is dark-grey in colour, like coal. It can be used just like other woods, despite being made of coal
Cave Fish:
Cave fish are fish that are present in underground water sources, including in the deep dark. They could be pale-pink, with larger fins, no eyes, and red cheeks. They would serve as a source of food in the deep dark
Sculk-Borer:
Sculk-Borers are a food source exclusive to the deep dark. They generate as small siphon-blocks, attached to deepslate. When the player gets within mining range, or somehow mines them some other way, they retract into the deepslate. If the deepslate is destroyed, the sculkborer will spawn in as a mob, and try to flee. They could appear as a sculk-colour-scheme snail with a siphon on the side of the head, and 2 small wavy things like on a sculk sensor. They would detect vibrations like a sculk sensor. They would drop sculk meat, which can be cooked and eaten, and sculk mantle, which can be used to make bundles or leather, like rabbit hide. If they escape, and leave the player's sight for a while, they would despawn and leave a siphon-block reseting to their original form
Cocoons:
Cocoons are pairs of silk blocks that can be found in the deep dark. Silk blocks are mechanically the same as wool blocks. Cocoons can be brown, grey, or black. When a block in a cocoon is broken, a silk-worm will spawn. Silk-worms are similar to silverfish, but larger and longer. They will attack the player that broke their cocoon, with attack-power and defence similar to a spider
Planetary travel
Chaostone
Whales and whalefalls