Your Constitution score increases by 1, your Wisdom score increases by 1 and your Dexterity score increases by 1

Crystal goblins mature faster than other races considered fully grown at the age of 3. Unfortunately, goblins are also a very short-lived race not because of the shortness or their natural lifespan but because the majority of them live brutal and short lives or do brutal and stupid things. The oldest goblin to date was a boggart elder, who had survived to the ripe old age of 43 until he fell into a patch of bog and drowned.

Crystal goblins are short, usually 3 to 4 feet and weigh about 50 pounds. Your size is Small.

Your base walking speed is 30 feet. 

Accustomed to life in dark and pitch-black caverns you have superior vision in dark and dim conditions. You can see in non-magical darkness and dim light as if it was brightly lit in a range of 90ft

You have tremorsense within a 30ft range of yourself. A creature with tremorsense is sensitive to vibrations in the ground and can automatically pinpoint the location of anything that is in contact with the ground and within range. If no straight path exists through the ground from the creature to those that it’s sensing, then the range defines the maximum distance of the shortest indirect path. It must itself be in contact with the ground, and the creatures must be moving. As long as the other creatures are taking physical actions, including casting spells with somatic components, they’re considered moving; they don’t have to move from place to place for a creature with tremorsense to detect them.

Shiny rocks are abundant, why not make them even shinier and use em as weapons? You gain the Magic Stone cantrip which does not count against your number of cantrips known

Crystal goblins diets consist entirely of rocks and as such they don't need to eat much, a single handful of rocks is equivalent to a days worth of rations to a crystal goblin. Their absurd diets have caused them to become immune to the poisoned status

Crystal goblins know when to run when things get heated. The goblin can take the Disengage or Hide action as a Bonus Action on each of its turns

You can speak, read and write Common, and Goblin