Finding something to attach to before giving up their mobility forever is a momentous choice for an oyster. For preference it will choose another oyster to settle on. The larvae are, it seems even at this stage, particular about the kind of foods they may eat – and after all that is pretty much an oyster’s main activity in life sorting out and filtering what it does what it does not want to eat - and if they cannot find what they want will drift on until they do or until they die. Possibly they are also listening out for the calling of the rest of the colony before committing themselves. They seem to have a primitive communication system, which attracts the larva to settle near other larvae and oysters as if the gathering of the colony is instilled in the DNA. They tend to cluster one on top of each other to the point oystermen often have to prise them apart before they suffocate each other.
While ostrea are still floating, they develop a pair of eyes (no one is fully agreed on their function) and a foot which they will use to glue themselves to their final resting place. At this stage they are catchily scientifically speaking called pediveligers.
If not to another oyster, then the young pediveliger will cling to a hard stationary object like a rock, a mangrove tree, a solid rock bottom of the estuary, the post of a pier. They have been found attached to bricks, boats, cans, tyres, bottles, even crabs, and turtles. If they are cultivated they will be ushered on to tiles, ropes, sticks, rafts, or bamboo.