ASI

Numerical Savant: Your species conceptualizes the world through pure mathematics and engineering. You gain proficiency in the Investigation skill and with two tools of your choice

You have no eyes and are completely blind. You have Blindsight out to a range of 120 feet, relying on high-frequency sonar. You are immune to the blinded condition, but you cannot perceive anything beyond this radius using sight. You are deafened in a vacuum or a zone of magical Silence, which reduces your blindsight range to 0 feet.

Your five-sided body plan and heavy mineral shell make you incredibly stable. You have advantage on saving throws and ability checks made to resist being knocked prone or moved against your will.

Your rock-hard composition provides defense. When you aren't wearing armor, your base Armor Class is 13 + your Dexterity modifier.

You cannot speak traditional vocal languages. Instead, you communicate via beautiful, multi-tonal musical chords. You can read and write Common and Eridian, but you can only "speak" by producing melodic tones. Other creatures can understand you normally if they have spent at least 24 hours learning your chords.