Fishmouth
From Roofing, Solar Power, and Spray Foam Insulation Wiki
Fishmouth
(Also referred to as an Edge Wrinkle)
(1) a half-cylindrical or half-conical shaped opening or void in a lapped edge or seam, usually caused by wrinkling or shifting of ply sheets during installation;
(2) in shingles, a half-conical opening formed at a cut edge.