Cryptic Trilobite has at least two +1/+1 counters on it.
Steps
Activate
Cryptic Trilobite's first ability by removing a +1/+1 counter from it, adding ({C} magic symbol) ({C} magic symbol) that can only be spent to activate abilities.
Activate
Ghave's second ability by paying ({1} magic symbol) and sacrificing
Young Wolf.
Young Wolf's undying ability triggers, returning it to the battlefield with a +1/+1 counter on it.
Resolve the
Ghave ability, putting a +1/+1 counter on
Cryptic Trilobite.
Activate
Ghave's first ability by paying ({1} magic symbol) and removing a +1/+1 counter from
Young Wolf, creating a 1/1 Saproling creature token.
Repeat.
Results
Infinite colorless mana that can only be spent to activate abilities.