It (they) may not be a cookie.
I tested using Slimjet here
http://browsercookielimits.iain.guru/ and got these results
Your Browser Test Results
15:7:22.761: Starting
15:7:22.892: Count: Max Cookie count with Character Length 3 and character "1": 180
15:7:23.711: Size: Max Cookie Character Length using character "1": 4097
15:7:24.441: Count: Max Cookie count with Character Length 4097 and character "1": 180
15:7:24.962: Size: Max Cookie Character Length using character "ÿ": 2049
15:7:25.879: Count: Max Cookie count with Character Length 2049 and character "ÿ": 180
15:7:26.73: Count: Max Cookie count with Character Length 100 and character "1": 180
15:7:26.267: Count: Max Cookie count with Character Length 10 and character "1": 180
15:7:26.467: Count: Max Cookie count with Character Length 5 and character "1": 180
15:7:26.515: Guessing Max Cookie Count Per Domain: 180
15:7:26.515: Guessing Max Cookie Size Per Cookie: 4097 bytes
15:7:26.515: Guessing Max Cookie Size Per Domain: NA