You have a +2 to Constitution and a +1 to Dexterity

You are an elemental but take the form of a humanoid when inhabiting armour

You are Medium (about 4–7 feet tall) or Small (about 3–4 feet tall), chosen when you select this species. Additionally, you can vary your height between the thresholds of your size category. e.g. If you are medium you can change your height from 4-7 feet. 

You have a speed 0f 30 feet when inhabiting armour, 50 feet when not inhabiting anything, and 0 feet when inhabiting most other objects.

You have Darkvision with a range of 60 feet.

Using an action you are able to inhabit a non-magical object that is no smaller than one inch on any side. This includes medium and heavy armour.

When inhabiting armour you gain the equivalent of mage armour(13+dex modifier) and your speed is reduced to 30. You still have disadvantage on stealth checks when inhabiting armour.

Using the hide action you can inhabit any non-magical object. You cannot move whilst inside of the object.

Using an action you can leave an inhabited object.

When not inhabiting an object, you can move through a space as narrow as 1 inch wide without squeezing. A creature that touches you takes 1d8 fire damage. In addition, you can move to a creatures space and stop there. The first time you enter the creature's space on a turn, that creature takes 1d8 damage; until someone takes an action to douse the fire, the creature takes 1d4 damage at the start of each turn.

You shed bright light in a 30-foot radius and dim light in an additional 30-foot radius. When inhabiting an object, you shed bright light in a 10-foot radius and dim light in an additional 10-foot radius. You also have disadvantage on stealth checks when in an area of no light or dim light.

For every 5 ft. the elemental moves in water, or for every gallon of water splashed on it, it takes 1 cold damage.

You know the Produce Flame cantrip. Once you reach 3rd level, you can cast the Burning Hands spell once with this trait as a 1st-level spell, and you regain the ability to cast it this way when you finish a long rest. Constitution is your spellcasting ability for these spells.

You can speak, read and right in all primordial languages. Additionally you can also speak in common through telepathy to any willing creature.

If they try to resist the telepathic link they must succeed a DC 10. On a fail you are able to communicate with them, on a success they are able to block out your communication.

You are immune to fire and poison damage.

You are immune to the conditions; exhaustion, petrification, poisoned, paralyzed and unconscious. In addition, when not inhabiting an object you are also immune to the conditions grappled, prone and restrained.