From Halopedia, the Halo wiki
Vanessa was a friendly shrubland animal who appeared each morning at Mann's and Henry Lamb's archaeological field site. Henry and Luther would scratch her head and rub her chin, causing her to make a purr-like sound. In truth, Luther was unsure of Vanessa's gender and merely imagined the creature to be female. Whenever she arrived to greet them, Luther would often feed her some lettuce from his knapsack.
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