[Source] The Eye of the Sun was a Force-imbued artifact that was created by a group of Jedi Masters for use during the Ruusan campaign as a defense against the Brotherhood of Darkness. It was later hidden under the ch'hala Heart Tree on Cularin and the Dark Jedi Len Markus tried to find it there in 19 BBY, because if he touched it against the Darkstaff, then the staff would gain enough power to destroy Cularin. It resembled a rock, but it could glow silver and a large yellow eye could appear on its surface, if it willed.