Yes, the bulbous ones have a hollow bulb. Ant colonies often live inside them. I soak mine upside down to keep the bulb filling up with water. As for soaking, I do think it depends on your conditions. A humid area probably does not need soaking at all. A dry area would. Also, if you live in a cold place with central heating, you may need to soak especially in winter. My best advice - take your recommendations from the plant itself. If leaf tips turn brown, soak. If base is turning brown (rotting) do not.
