Shabbos 2:3

The only tree product that may be used as a wick is flax. Furthermore, the only tree product that is susceptible to ritual uncleanliness because of a corpse under a canopy is flax. If a piece of a garment was folded into a wick but not singed in the fire to temper it, Rabbi Eliezer says that it is still a garment, and therefore susceptible to ritual uncleanliness and one may not light with it. Rabbi Akiva says that it is no longer a garment, and therefore not susceptible to ritual uncleanliness and one may light with it.

Shabbos 2:4

One may not poke a hole in an eggshell, fill it with oil, and position it to drip into an oil lamp on Shabbos – one may not even do this with earthenware, though Rabbi Yehuda permits it. If the potter connected such a receptacle at the outset, it is permitted because it's all one vessel. One may not fill a dish with oil and place it next to the lamp so that the wick can draw from it but Rabbi Yehuda permits it.