So, today while sleeping i had put my palm just under top of the cleft. A bone got rubbed and felt watery. Idk if its tailbone, but towards the right side on my buttock just beside the cleft i feel a bone, i asked my mom, she said she has it on her left side. But when i palpate that bone and press on it, it feels bubbly/watery? Is it because of the muscles present over it or any pus or something has formed? (I read about some cyst). I don't have any symptoms though, please help me understand if this is normal.