Things that appear on trees

What's this!?

A fruit?? A weird insect? A strange slug? AN ALIEN!?

Noooo, it's just a new gall in an oak tree!!

There were some more...

They were on a Quercus robur tree. Have you ever found something like this on oak trees?

I only started learning to look for galls recently, and it's an all-new​ world of information and relations among species!!

Please do not forget to check the other daily photography initiatives:
Weekday Challenges:

• Monochromemonday - initiated by @old-guy-photos
• TreeTuesday - initiated by @old-guy-photos
• BeachWednesday - leaded by @lizanomadsoul and initiated by @uwelang
• SunThursday - leaded by @lizanomadsoul and initiated by @uwelang
• LoveFriday - initiated by @liliana.duarte
• MarketFriday - initiated by @dswigle
• DanceWeekend - initiated by @uwelang
• MetalWeekend - initiated by @detlev
• SaturdayView - initiated by @luxurylifestyle
• Caturday - initiated by @dswigle
• BeautifulSunday - initiated by @ace108
• IntroduceYourHomeTown - initiated by @redtravels
• BeautifulDay - initiated by @barbara-orenya

...and challenges

• Something About Me Challenge - initiated by @bluemoon
• BeerSaturday - initiated by @detlev
• ColorChallenge (with daily color tags too) - initiated by @kalemandra
• Bwphotocontest - initiated by @daveks
• MyPictureDay - initiated by @timsaid
• DailyPhotoContests by @juliank: (- Monday: #foodphotography and #animalphotography; - Tuesday: #landscapephotography and #cityscapephotography; - Wednesday: #architecturalphotography and #vehiclephotography; - Thursday: #macrophotography and #colourfulphotography; - Friday: #streetphotography and #portraitphotography; - Saturday: #sportsphotography and #smartphonephotography; - Sunday: #goldenhourphotography and #longexposurephotography.