The chip on a credit card looks really similar to a SIM card
If you look closely, the chip on a credit card looks really similar to a modern SIM card.
Originally, SIM cards were the same size as a credit card. This is because they are defined by the same ‘smart card’ standard (85.60 x 53.98 mm, ISO/IEC 7810 ID-1). Over time, they were miniaturized while keeping the same electrical contacts defined by the ISO/IEC 7816 standard.
Modern SIM cards (mini, micro, nano) are approaching just the chip portion of that original card.