A massive fin-shaped slab of hot rock has recently been seen growing in the crater of Washington State’s Mount St. Helens.

The feature is the seventh such structure to rise in the volcano’s crater since it began slowly erupting in October 2004, say scientists with the U.S. Geological Survey’s (USGS) Cascade Volcano Observatory.

Clear skies following a long, cloudy, wet winter in the U.S. Pacific Northwest recently lifted the veil on this latest formation.