Check the base first
A black, soft, or smelly base is a serious warning sign. The plant may have stayed wet too long, especially if leaves pull loose from the center.
Review recent watering
Long soaks, closed containers, and returning the plant while wet can all contribute to rot. The problem is usually water plus poor drying, not watering alone.
Remove it from the display
Take the plant out of glass, shells, moss, or holders and let it dry in open airflow while you inspect it. Do not keep adding water before you know whether the base is firm.
Separate black tips from black base
Dark dry tips may be old damage, mineral buildup, or sun stress. A black base or black center is much more urgent because it can mean internal rot.
Check for heat or sun burn
Blackened patches on exposed leaves can follow hot direct sun through glass. Move the plant to bright indirect light and watch whether new damage stops.
Know when recovery is unlikely
If the center pulls apart or the base collapses, the plant may not recover. Firm green or silver tissue gives you a better chance than mushy dark tissue.
Prevent the same issue
Water air plants outside tight displays, shake out hidden droplets, and choose holders that let the base dry fully after each watering.
Protect the rest of the collection
If one plant rots in a shared setup, inspect nearby plants and the display. The same trapped-moisture routine may be stressing more than one plant.