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Tendrils of dark interstellar gas and dust surrounding, and pointing toward, massive stars are called elephant trunks. These tendrils form when the star’s copious ultraviolet radiation ionizes and disperses the more tenuous gas around it. Dense clumps remain, at least temporarily, and may shadow columns of gas lying behind them. The tendrils appear dark because the gas contains dust grains, which block the background light. Young stars may be present in the densest clumps at the tips of the trunks. These tips, where ionization is ongoing, also glow. A well-studied region containing elephant trunks is the Eagle Nebula (M16) in the Serpens Constellation.