Generally in a bag of water with some air space to allow air exchange. Try to clean out the caulerpa (remove
detritus) before bagging it so it doesn't foul the water. The longer you take to ship it the better the chance it can "go sexual" during shipment and kill itself.
Also remember that shipping of caulerpa into and out of California is mostly against the law. Almost all species of caulerpa are banned in that state as they are considered (rightfully so) potentially invasive species.
The last I heard Florida was also considering similar laws, but don't know what became of them.
Brian
