Natural Born Digger

You gain a burrowing speed, what else is there to say?

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You gain a burrow speed equal to half your movement through earthy materials, such as soil or sand.

Whereas you gain a burrow speed equal to a quarter of your movement through untreated stone, e.g caves

You gain 10ft of Tremorsense. (A monster with tremorsense can detect and pinpoint the origin of vibrations within a specific radius, provided that the monster and the source of the vibrations are in contact with the same ground or substance. Tremorsense can't be used to detect flying or incorporeal creatures.)