The TOMB token is an algorithmic stablecoin pegged to 1 $FTM via Seigniorage.
This is a stablecoin with a flexible money supply. The algorithm has a program that regulates $TOMB buying and selling. In this way, It keeps the peg to the $FTM token price. Currently, a large percent of $FTM supply is locked in staking. This means that with a fixed supply, FTM will run short over time.
The design of the TOMB token is to use it as the main currency in place of $FTM. They want to be the main medium of exchange for Fantom Opera and create a bi-token system, $FTM for gas and staking, and $TOMB for transacting. TOMB actively pegs through the algorithmic mechanism, but it's not hardpegged to FTM. Therefore, it's not always at a 1:1 peg ratio and can fluctuate above and below.
This is important in understanding the different coins used in Tomb Finance that achieve the peg.
$TSHARE is the main contributor to the peg in it's expansion periods, whenever the peg of TOMB-FTM goes 1.1 or higher, by staking this token you can benefit from the printing of new $TOMB, by creating new tokens and increasing the supply this pulls the price back slightly and looks to achieve 1:1 peg parity.