Am pretty far along on baby's first homebrew race, but I've run into a hiccup: These are grub-people with an uncanny knack for feeling vibrations of the earth, even if they are above ground. (a la blindsense) If I wanted to make this a viable racial trait/ability, how would I make it functional? If you need any additional info, please ask.
NOTE: Tremorsense and Blindsense are both pretty good, but I found a good way to do it (unfortunately can't think of a good name, I thought tremor sense was a good name until I learned it was already a thing). Thanks to everyone who answered! ^^
When an unseen object or creature within 30 feet above ground or 20 feet underground is approaching on foot or via burrowing underground, the player should be asked to roll a perception check. If this check succeeds, the PC now knows that something is approaching, but has no additional information such as size or number of approaching objects or creatures. Then the player may roll an additional perception check for honing their to determine either a rough estimate of the approaching force’s size or numbers.