Tombolos are formed when a wave circles around
a small land mass(t
hat includes rocks)and collide between the small land mass and the big land mass.
That builds up sand between the small land mas and the big one creating a tombolo.
Old tombolos can have trees growing on it!
See some Tombolos in Hong Kong, china! here:
Ma Shi Chau
Sharp island's Kiu tau island tombolo