Steganography has been widely used to embed secret data in cover multimedia carriers including digital image, audio, and video files such that the confidential information being communicated is hidden. Immersive multimedia, e.g., 360° videos, have recently received increased attention as promising applications for the Internet and 5G mobile networks. In this paper, we focus on using steganography for hiding secret data in an immersive multimedia carrier. Specifically, a spherical least significant bit (LSB) data hiding approach is proposed to embed secret videos in 360° cover videos along with morphological operations. Due to viewers are paying less attention to the North and South Poles compared to the Equator region of 360° videos, LSB data hiding is performed around the poles of the equirectangular projection of the sphere to the plane. Data hiding capacity is increased by using morphological operations in the remaining mid-region around the Equator which broadens the edge area for embedding secret data. The proposed spherical LSB data hiding technique may be used to hide secret videos or other confidential data in 360° cover videos. It can also be used to increase available bandwidth for communication purposes as long as embedded data has no significant impact on the quality as perceived by the end-user. A performance assessment of the proposed approach is conducted with respect to data hiding capacity and objective perceptual video quality. Numerical results are provided for a wide range of scenarios illustrating the trade-offs between capacity and quality.