What hidden items regenerate and what is the timing for this?

I went back into Relic Passage in order to deal with the Surfing things, and I saw that a rock that I had previously plundered now had a hidden item again (a Shard). Are there are any other hidden items that regenerate, and if so where and what are they? Also, how often do they regenerate.

Pleaselog inorregisterto add a comment.

There are 4 different rocks in Relic Path that give 1 shard each. Are you sure you have not gotten mixed up?? As far as I have found, Items only regenerate in the Hidden Grottos.

This source,Bulbapedia/ Recurring Items, mentions nothing about Relic Passage, staing only the Hidden Grottos.These are things that can be found in the Hidden Grottos. After you have taken something from the Grotto, there is a 5% that you will find an Itemora Pokemon again every 256 steps.All these items can be found in any Grotto.

Boldare hidden within the Grottos, so use the Dowsing Machine.

Damp MulchGrowth MulchStable MulchGooey Mulch

RepelSuper RepelMax Repel

Poké BallGreat BallUltra Ball

PotionSuper PotionHyper Potion

TinyMushroomBig Mushroom

Rare CandyPP UpPP Max

Red ShardGreen ShardYellow ShardBlue Shard

These stones can only be found in specific Grottos.They follow the same rules of regenartions.

Routes 2, 3 (dark grass), 5, 6 (near Breeder), 7, 9, Floccesy Ranch

Route 6 (Mistralton Cave)

Route 3 (pond)

Source:Bulbapedia/ Hidden Grottos