# Function: growthCost()

[**lifecycle-kit**](https://jonbogaty.com/lifecycle-kit/api/readme/index.md)

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[lifecycle-kit](https://jonbogaty.com/lifecycle-kit/api/readme/index.md) / [chem](https://jonbogaty.com/lifecycle-kit/api/chem/readme/index.md) / growthCost


# Function: growthCost() {#function-growthcost}


> **growthCost**(`id`, `backbone?`): `number`

Defined in: [chem/biomolecules.ts:155](https://github.com/jbcom/lifecycle-kit/blob/074e4e7b8038d3e2de9eb44c4b5b5aee0ef02b48/src/chem/biomolecules.ts#L155)

How costly a tissue is to grow, from the scarcity of its elements.

Mineral needs phosphorus, which is roughly five orders of magnitude rarer
than oxygen, so skeleton is genuinely expensive and a heavily built
creature is genuinely an achievement.


## Parameters {#parameters}



### id {#id}


`string`


### backbone? {#backbone}


[`Backbone`](https://jonbogaty.com/lifecycle-kit/api/chem/type-aliases/backbone/index.md) = `"C"`


## Returns {#returns}


`number`