The easy-care houseplant trend started with cacti - but for those who want a less spiky look but the ease of a succulent, lithops may be the answer.
Commonly known as pebble plants, or living stones due to their uncanny resemblance to pebbly forms, lithops have a stony camouflage to avoid predation from passing grazing animals in the wild, says Alex Hankey, trials team leader at RHS Garden Wisley, who collects lithops.
Native to South Africa and Namibia, they grow in very open, exposed rocky plains, which receive very little rainfall, so have adapted to survive drought with a swollen pair of leaves that store water. These water-filled leaves would provide a perfect snack for a passing thirsty animal, hence the stone-like camouflage.
As houseplants, they look fantastic, like multi-coloured living stones that can produce daisy-like flowers - hence why they're so popular on social media.
Each variety is as easy to care for as any other. Hankey's personal favourites are Lithops dorotheae and Lithops otzeniana, as they have incredible patterning on their leaves. In the wild they will flower in the late winter or early spring, but in cultivation in the UK, they flower in late summer and early autumn (September-October).
Here's what else you need to know about them...
Where should you keep them?
"They should be kept inside the greenhouse year round to control watering. If they are out in the elements they will receive too much rain as British summers are still too wet for them," says Hankey.
What soil do they need to thrive?
"A very free-draining, loam-based growing media is required, including plenty of added sand and grit. They don't require a fertile soil."
How much watering do they need?
"Not much. Don't water from October through to April, as this will encourage rotting. During the winter months they will be slowly growing a new pair of leaves that will push through the centre of the old leaves," explains Hankey.
"These old leaves will wither and die over the winter or spring. Don't make the mistake of thinking the plant needs watering as the leaves get older and wither. Watering thoroughly once a month during spring and summer is sufficient."
What other interesting qualities do they have?
"Seed capsules, whose opening is triggered by water. When wet, the seed capsule slowly unfurls forming a star shape, which then allows the seed to be splashed out of the capsule by rain droplets."
How tough are they?
"They are cold tolerant (down to 2-3 degrees Celsius), but not frost hardy," notes Hankey. "They should be grown in a greenhouse that is kept frost-free during the winter and well ventilated in the summer."
What's their ideal situation?
"They require a very sunny location, as they will etiolate (stretch to the light) if it is too shady. If growing on a windowsill, it needs to be south-facing. Rotating the plants every week will prevent them stretching towards the light source."
How can you show them off?
"They can be displayed individually in terracotta pots with a top dressing of grit," suggests Hankey. "Alternatively, many different varieties can be grown in a large pan or trough and rocks/stones carefully positioned to make your display look very naturalistic."