A transient data structure is a combination of an ephemeral data structure, a persistent data structure, and fast conversions between them. We present a transient sequence data structure that supports efficient read and write access at an arbitrary index with worst-case cost $O(K\log_K n)$, insertion and extraction at either end with worst-case cost $O(K\log_K n)$, and splitting and concatenation with worst-case cost $O(K\log^2_K n)$, where $K$ is a user-defined chunk size. We provide a detailed analysis of this data structure and show that, in many favorable scenarios, it performs much better than these pessimistic worst-case bounds might suggest. Furthermore, we describe its implementation and provide an experimental evaluation of its performance. We believe that it is a good candidate for a one-size-fits-all, general-purpose sequence data structure.