If something is spongier, it is softer and has more holes, like a sponge.
Spongier things might make people think of being wet, squishy, or good for cleaning.
Examples:
The sponge is spongier than the rock.
The bread is spongier than the cake.
The spongier bread is better for soaking up soup.
I wish my bed was spongier.
A spongier sponge can hold more water.
The spongier the bread, the better it is for sandwiches.