The Olmec were the first great culture to be built in Mexico and Central America. They built a city on a river island in 1200 B.C. or so: archaeologists, who do not know the original name of the city, call it San Lorenzo. San Lorenzo had no rivals: it was the largest and most magnificent built city in Mesoamerica at the time and it was an influence in the region. Archaeologists consider the Olmec to be one of only six “pristine” civilizations: these were cultures that developed on their own without the help of migration or influence from some other civilization.
They built this Olmec out of stone this is what it looks like...
see this is what it looks like and there is a video about the Olmec.
The Olmec culture thrived along Mexico’s Gulf Coast from approximately 1200-400 B.C. The first great Mesoamerican culture, it had been in decline for centuries before the arrival of the first Europeans, so much information about the Olmec has been lost. We know the Olmec primarily through their art, sculpture and architecture. Although many mysteries remain, ongoing work by archaeologists, anthropologists and other researchers has given us idea of what Olmec life might have been like. So Spain invaded and destroy the Olmec. Some wasn't destroyed and some survived. That's why it was lost, it got destroyed or it fell into the water or lakes and river.