Content-Type: text/shitpost

An oculus can also be a hollow stone.
According to Church-Lore Gleanings:

In some cases buried hearts have been accidentally discovered little or no trace being left to identify them with any certainty. At Waverley Abbey Surrey in 1731 there were found in a stone oculus two leaden dishes soldered together containing a human heart well preserved in pickle…

(Thomas Firminger Thiselton Dyer, 1892. p. 133))