Mirabilis was the name of the Israeli company that produced ICQ ("I seek you"), which in the 1990s was the most popular form of Instant Messenger. Mirabilis was founded in 1996 by Arik Vardi, Yair Goldfinger, Sefi Vigiser and Amnon Amir, and was purchased by AOL less than two years later.
AOL ran ICQ and AIM (AOL Instant Messenger) as independent products, which helped to create an illusion of a competetive marketplace. Eventually AIM and ICQ were merged, beginning in roughly 2001.
Mirabilis is now owned by Time Warner.