What is this thing in my tailight assembly?

[Deej101]

Pics of both taillights below, you can see one is missing.

It has like a small piece of foam in it. What function does this piece serve, and can I live with one missing?

Thanks for any insight.

2001 SR5

 

[HiluxSurf SSR-G]

it seems to be a breather

 

[calicojax]

blinker fluid breather valve. Hard to find a good one.:hunter:

 

[02_SE_Runner_DAD]

Looks like a breather.

 

[Devbot]

Already stated above. If I'm not mistaken, if you find your tail lights are fogging up you can pull them off and it'll help vent the excess moisture inside