Ha! That was my initial reaction too.

Here's another option, it's possible that someone dumped a bottle stop-leak in there. Sometimes that accounts for odd colors and strange things in the coolant.

__________________
'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman