122 Nature with Glitter
The left part (1999 Duplo spider web) is known to be color 122. The right brick, made for the Allianz Arena in LegoLand Deutschland, matches 20 Nature (plus sparkles), but it's obviously entirely different from the web. Since "nature" refers to the "plain" material without colorant, the uncolored rubber web and the uncolored ABS are both referred to as "nature".
Does not glow under a UV light.