That will settle out of water. (Doesn't mix well with water).
Fenbendazole (Safeguard) dosing is by weight, so treat each bird individually.
To treat Roundworms Only - Safeguard dose is 0.23ml per pound of weight given orally once, then repeated in 10 days.
To treat most worms that poultry can...
Photos would be helpful, if you see it again, please post photos.
Since you are not sure if what you saw was a pine needle or something else, I think I'd wait on deworming unless you take a sampling of poop to your vet for a fecal float - this test will tell you if you need to deworm or not.