Styrofoam!

it could I would use a frisbee instead.

Where do you think the styrofoam eggs at the craft store come from?

Kidding! (someone said that years ago and I still remember it)

The birds should be okay but I would keep styrofoam away from them from here forward. For some reason chickens go crazy for styrofoam - there are a bazillion posts about this. 
Watch them carefully though and report if they seem ill in any way.

JJ

Yeah, go with a metal pan or hard plastic plate. I'm convinced chickens like the squeak of styrofaom on their beaks.

It'll go through them and be fine.

Probably not a good thing for their diet--certainly no food value.  Mine once got at some styrofoam insulation I have around the base of my greenhouse.  Didn't seem to bother the birds but I covered it up fast.  Had a friend tell me the birds were going to poop their own egg cartons.

Our chickens actually mine for styrofoam.  They dig holes to get at the stuff underground around the foundation.  Yep regular miners.  They have eaten plenty.  We had a problem, one ate a big chunk and got it stuck in its throat.  Almost lost that chick, had it in the "hospital" for several days.
ON

Mmmm styrofoam.  Chickens love styrofoam.  Luckily they seem to tolerate eating it pretty well.  I wouldn't purposely give it to them but I've heard of large amounts of styrofoam insulation or entire incubators drying in the yard being eaten with the chickens having no problems.  At minimum stick to paper plates.  I use those plastic pans for rabbit cages to throw treats on.

Gosh, I must be a total redneck or sumpin' - I toss their treats on the GROUND in the run!  (When I'm not feeding them from my hands.)

Lawdy, lawdy.  Whut kin I find to use fer chicken treats?  Already use one o' them baking trays fer a shaller waterer and toesies cooler-offer!

Must rethink this.  What WILL the neighbors say???

It's a chickens version of pop corn

Just think if they fall in the pond they will not sink, i think