Depending on model year and trim level of Camry, some of them don't have engine immobiliser. It looks like yours is one of them. One good indication is the sub key(the one you didn't lose) that can start the car but can't open the trunk is a all metal one. That means it doesn't have built-in chip. Does your sub key look like that? If so you really don't need to buy the master key with built-in chip.
By checking the VIN, the guy at dealership can quickly know if your car need built-in chip or not. Certainly they know the tooth partern of the master key as well.
The difference between your master key and sub key is as follows:
- Master key has extra rubber/plastic to its handler(What you describered as "頂部小包")
- Sub key has one less tooth so it can't open the trunk and glove box
Do you have user mannual for your Camry? If not, you can register and download a free soft copy(PDF file) from Toyota website. It has detailed description on this, as well as other info you might find helpful later on.
