Like others said, we don't really know, but most likely, they just got eaten, ingested, or sopped up by cellular life when it arrived. They couldn't have been m

Like others said, we don't really know, but most likely, they just got eaten, ingested, or sopped up by cellular life when it arrived. They couldn't have been much more than symbiotic molecules, not complex things like modern cells with organelles that we know today.