Echidna Lamia

Unlike the other lamia-kin, the Echidna are quite homebound and seldom venture out of their coastal territories. As the largest of their kind, the echidna are well able to guard their homes from invaders or trespassers.

Bite. Your jaws are natural melee weapons, which you can use to make unarmed strikes. If you hit with them, you deal piercing damage equal to 1d6 + your Strength modifier.
Fanged Embrace. When you successfully grapple a creature you can use a bonus action to make an unarmed attack using your bite against the grappled creature until the end of your turn.
Fitness. You are proficient in Acrobatics or Athletics.
Natural Armor. Your body is covered in tough scales. When you aren’t wearing armor, your AC is 13 + your Dexterity modifier. You can use your natural armor to determine your AC if the armor you wear would leave you with a lower AC. A shield’s benefits apply as normal while you use your natural armor.