You must have SKELETON and GRANITE BLOCK to make TOMBSTONE. You can find this item in signs category. It takes 9d22h57m05s to grow TOMBSTONE from seed to tree. Nice experience you find in these blocks. There is no data about durability. Oops, there is no entry in the database about seedratio. If you know something, please share. Oops, there is no entry in the database about gemratio. If you know something, please share. Oops, there is no entry in the database about blockratio. If you know something, please share.