what app is making this notifications?

Hello all:
i have an app for telling me the time each 15 minutes, but i forget what is this app,
i need to stop it's notifications compleetly.
I terned all it's notifications and banners off, except sound, because i do not want a banner each 15 minute,
so, how can i find this app now? is there a trick to know what notification happened now even if it does not have banners or something in the control center?