[oneshtein]

A symbol may look differently than original letter, for example N - №, € - E (Є), S - $, integral, с - ©, TM - ™, a - @, and so on.

However, those symbols doesn't have lower case variants. Moreover, lower case k means kilo-, not a «smaller Kelvin».

[bee_rider]

Although it is a prefix in that case, so we should expect to see k alone.

To maximally confuse things, I suggest we start using little k alone to resolve another annoying unit issue: let’s call 1 kilocalorie “k.”