Abstract: A pipeline pig is provided which is especially adapted for use in conjunction with laying offshore pipelines in that it detects and indicates dents, and other disconformities in the nominal cross-sectional configuration of the pipeline which may occur as a result of the laying of the pipeline. It employs a plurality of prolate spheroid rollers arranged to secure substantially full circle coverage of the pipeline and yet only a minor portion of the length of the rollers will be normally in contact with the pipeline thereby reducing the wear on the remaining portions of the rollers and increasing the ease with which the pig can be towed along the pipeline. In another aspect, a system is provided in which a pig includes with a means of sensing a condition along the pipeline and a memory means for storing the output of the detecting means.