A crunchy pink mass sticking out of a wall may look concerning, but it can sometimes be ordinary spray foam insulation. Construction and repair crews use expanding foam to seal gaps around pipes, windows, wiring, and door frames. Depending on the manufacturer and product, spray foam can appear pink, yellow, blue, orange, or other colors, so color alone cannot reliably identify it.

The foam expands as it cures and may push through cracks or extend beyond the space it was intended to fill. When excess material isn’t trimmed, it can leave behind uneven, bubbly formations that eventually harden. However, it’s best not to touch or disturb an unfamiliar substance, especially if it may still be uncured, since fresh foam can irritate the skin and eyes and should be used with appropriate ventilation.

Other clues can point to a different problem. Damp drywall, stains, musty odors, or spreading patches may indicate moisture damage or mold, while holes, movement, or scratching sounds could suggest pests. If the material is confirmed to be cured spray foam and the surrounding wall is dry, small amounts of excess foam can often be carefully trimmed and covered, while larger areas or fire-rated walls are better assessed by a professional.

Taking photos from several angles and noting the material’s texture, smell, location, and changes over time can make identification easier. In many cases, an unusual wall formation turns out to be harmless insulation rather than something living or dangerous. Still, checking carefully is worthwhile to make sure an underlying moisture, structural, or pest issue hasn’t been overlooked.