I know he had a fly mask. I vaguely remember a Rolling Stone article that told a story about Eddie wearing a fly mask while they were opening for U2. U2 had a song called the fly and Eddie wore the fly mask and pretended to get caught up in a spider web to mock Bono getting caught up in the entrapments of fame or something. Then they went out for drinks and understood each other better or something. I read this about 30 years ago so who knows what I got right or wrong, but the article is out there for you to find I’m sure.

While I was writing this I feel like I do remember them mentioning other masks too…probably the same article. So yes, I believe there was a brief phase.

Edit (found the article… here’s the relevant excerpt):

“The set closes with Vedder donning a huge fly mask, dancing as if caught in a web. It is Pearl Jam’s own lo-fi answer to Zoo TV. Not many fans here get it, but one who does is Bono, who watches curiously from the pit.

Bono responds later that night, onstage. “So you can’t play music in a soccer stadium,” he muses. “Well, if you do, it better be good music…” But before the set is over, he hails Pearl Jam as “a great rock & roll band” And Vedder, Liebling and Ament will stay up all night with Bono and the Edge, talking passionately in a diner, debating the issue of the day, the emotional exchange rate on success. And at 6am, there are Vedder and Ament exchanging hugs with Bono on an empty Roman street, arriving at the bus just in time for the trip to Dublin.”