A method for testing the performance of surface coatings on the formation of biofilm and encrustation on materials. The creamers can be shelf-stable and aseptic. When the leg part is inserted into the female member in a state in which the spike-like projection bites an end of a cord inserted into the female member from the other open end of the female member and drawn out from the one open end, the end of the cord is held between the spike-like projection and an inner surface of the female member. If decoding processing does not end within the predetermined limit time, only decoded data are written in a memory.