+**129d** represents a long-lived [Isotope](/wiki/Isotope) of iodine, a naturally occurring [Element](/wiki/Element). Its enduring radioactive decay serves as a valuable tracer in geological and environmental studies, charting processes across immense spans of time.
+## See also
+- [Radioactivity](/wiki/Radioactivity)
+- [Half-life](/wiki/Half-life)
+- [Nuclear Decay](/wiki/Nuclear_Decay)
... 1 more lines