Yes — that looks like a buildup of soap residue, grime, and biofilm around the drain/plug, which can also cause that nasty smell.
🧽 Try this first
- Remove the plug/strainer if you can.
- Put on gloves and scrub the metal around the opening with an old toothbrush or small cleaning brush and hot water + dishwashing liquid.
- For the black buildup that won’t come off, apply 3% hydrogen peroxide, leave it for about 10 minutes, then scrub and rinse thoroughly with hot water.
- Clean the underside of the plug as well — this is often where the smell-producing buildup hides.
- Run very hot water down the drain for a few minutes.
🚿 If it still smells
The problem may be deeper in the P-trap (the curved pipe underneath the sink). Put a bucket underneath, remove the trap, clean out the sludge inside, rinse it thoroughly, and reinstall it securely.
Important: Don’t mix bleach with vinegar, ammonia, drain cleaner, or other cleaning products. If you use a commercial drain cleaner, follow its label exactly.
If the black material keeps returning quickly or the smell remains after cleaning the trap, there may be a drain/sewer or plumbing issue rather than just surface dirt.